Allow use of environment variable for storing access token

This Item has been extended.

It is currently not ideal having to provide the API bearer token as an argument in its full form for CLI commands.

Adapt to allow for the token to be set as an environment variable - either use a default token env variable or allow it to be specified on the command line.

E.g.

set token "some_token_string"

python -m lascli list curves -c "path/to/config.json" -u "https://osdu-ship.msft-osdu-test.org" --welllog_id "some_welllog_id_string" --verbose -t $token

There are a number of arguments on the command line that could be consolidated.

• The base URL could go into the config file.
• There could be a default config file path.
• There could be a default token environment variable name.