Inception

Remove positional arguments for credits, debits, reversals, refunds, etc.
Create holds directly.
Scenario updates.
Created Balanced singleton. Moved client to it.
Ensure thread safety.
Now do Balanced.configure("API_KEY") to match other client libraries.
Allow credit a new bank account (same payload).
Added more resource fields to card such as postal_code_check, security_code_check, is_valid, and is_verified
More tests.
General cleanup.

NOT READY FOR MERGE.