Restructure of LAS to wellbore/well log record mapper

Closes #14 (closed)

Merge Request 9 includes all changes from this branch - when it is merged this will no longer be necessary.

The main record mapper has been split into two parts:

• The LasToRecordMapper (accessed externally and instantiated with a LAS data object and a config file)
• The attribute builders (accessed only by the LasToRecordMapper for building components of the required record object)

There is also now a RecordConfig class for storing the configuration variables.