Update JupyterNotebook example to use url

examples/JupyterNotebook/OpenVDS_basic_usage.ipynb

 %% Cell type:code id: tags:
 
 ``` python
 import openvds
 import matplotlib.pyplot as plt
 import matplotlib
 import matplotlib.image as mpimg
 import numpy as np
 import time
 %matplotlib inline
 matplotlib.rcParams['figure.figsize'] = (16, 16)
 ```
 
 %% Cell type:markdown id: tags:
 
 ## Open a VDS connection and get the Layout object for the connection
-Specific OpenOptions has to be used to open a connection to different cloud vendors. The AWS open options also relies on the AWS standardized credentials file in $HOME/.aws/credentials
+Specific OpenOptions can to be used to open a connection to different cloud vendors. The AWS open options also relies on the AWS standardized credentials file in $HOME/.aws/credentials
+
+Alternativly a url and connection string pair can be used. This scheme is descibed here:
+http://osdu.pages.community.opengroup.org/platform/domain-data-mgmt-services/seismic/open-vds/connection.html
 
 %% Cell type:code id: tags:
 
 ``` python
-error = openvds.Error()
-openOptions = openvds.AWSOpenOptions("bucket", "folder_in_bucket", "region")
+#openOptions = openvds.AWSOpenOptions("bucket", "folder_in_bucket", "region")
 #openOptions = openvds.AzureOpenOptions("connection_string", "container", "blob") #blob is ignored for now
 #openOptions = openvds.GoogleOpenOptions("bucket", "folder_in_bucket")
-vds = openvds.open(openOptions, error)
+#vds = openvds.open(openOptions)
+vds = openvds.open("some url", "optional connection string")
 layout = openvds.getLayout(vds)
 ```
 
 %% Cell type:markdown id: tags:
 
 ## Layout
 The layout can be used to retrieve properties about the VDS.
 
 %% Cell type:code id: tags:
 
 ``` python
 print("ChannelCount: {}".format(layout.getChannelCount()))
 for i in range(layout.getChannelCount()):
     print("  Channel Name: {}".format(layout.getChannelName(i)))
     print("    Value range: {} - {}".format(layout.getChannelValueRangeMin(i), layout.getChannelValueRangeMax(i)))
 
 print("Dimensionality: {}".format(layout.getDimensionality()))
 for i in range(layout.getDimensionality()):
     print("  Dimension name: {}".format(layout.getDimensionName(i)))
     print("    Number of samples: {}".format(layout.getDimensionNumSamples(i)))
     print("    Coordinate min max {} - {}".format(layout.getDimensionMin(i), layout.getDimensionMax(i)))
 ```
 
 %% Cell type:markdown id: tags:
 
 ## Metadata accessor
 Metadata can be accessed through the layout objects getMetadataXX function. The type is part of the key and no implicit conversion will occur.
 - getMetadataInt
 - getMetadataIntVector2
 - getMetadataIntVector3
 - getMetadataIntVector4
 - getMetadataFloat
 - getMetadataFloatVector2
 - getMetadataFloatVector3
 - getMetadataFloatVector4
 - getMetadataDouble
 - getMetadataDoubleVector2
 - getMetadataDoubleVector3
 - getMetadataDoubleVector4
 - getMetadataString
 - getMetadataBLOB
 
 
 
 %% Cell type:code id: tags:
 
 ``` python
 MetaType = openvds.MetadataType
 if layout.isMetadataDoubleVector2Available("SurveyCoordinateSystem", "Origin"):
     print("SurveyCoordinateSystem::Origin: {}".format(layout.getMetadataDoubleVector2("SurveyCoordinateSystem", "Origin")))
 if layout.isMetadataDoubleVector2Available("SurveyCoordinateSystem", "InlineSpacing"):
     print("SurveyCoordinateSystem::InlineSpacing: {}".format(layout.getMetadataDoubleVector2("SurveyCoordinateSystem", "InlineSpacing")))
 if layout.isMetadataDoubleVector2Available("SurveyCoordinateSystem", "CrosslineSpacing"):
     print("SurveyCoordinateSystem::CrosslineSpacing: {}".format(layout.getMetadataDoubleVector2("SurveyCoordinateSystem", "CrosslineSpacing")))
 #layout.getMetadata("SEGY", "TextHeader", openvds.core.MetadataType.BLOB)
 #layout.getMetadata("SEGY", "BinaryHeader", openvds.core.MetadataType.BLOB)
 ```
 
 %% Cell type:markdown id: tags:
 
 ## The AccessManager api
 The AccessManager api can be used to retieve data from the vds
 
 %% Cell type:code id: tags:
 
 ``` python
 accessManager = openvds.VolumeDataAccessManager(vds)
 axisDescriptors = [layout.getAxisDescriptor(dim) for dim in range(layout.getDimensionality())]
 sliceType = 'inline'
 sliceIndex = 55
 sliceDimension = 2 if sliceType == 'inline' else 1 if sliceType == 'crossline' else 0 if sliceType == 'timeslice' else 0 if sliceType == 'depthslice' else -1
 
 min = tuple(sliceIndex + 0 if dim == sliceDimension else 0 for dim in range(6))
 max = tuple(sliceIndex + 1 if dim == sliceDimension else layout.getDimensionNumSamples(dim) for dim in range(6))
 
 req = accessManager.requestVolumeSubset(min, max, format = openvds.VolumeDataChannelDescriptor.Format.Format_R32)
 height = max[0] if sliceDimension != 0 else max[1]
 width  = max[2] if sliceDimension != 2 else max[1]
 
 data = req.data.reshape(width, height).transpose()
 cmap=plt.get_cmap("seismic")
 plt.set_cmap(cmap)
 plt.imshow(data)
 ```