Added ability to create a new identity.
Added a get_balance method to Account, as well as tests for Account.
Now posting JSON strings instead of dictionaries. I needed to do this in order to be able to post nested dictionaries (in particular the 'lines' of the JournalEntry).
Added basic JournalEntry functionality.
Forgot to import JournalEntry in __init__py
Merge pull request #1 from DisruptiveLabs/master

Extending functionality, including basic JournalEntry capability.

Thank you Julian!