Dispute, Fee Details and Invoice updates

In an attempt to resolve #13 ("'Disputed' attribute on charge is deprecated in favor of 'dispute'") I discovered that quite a few unit tests were failing due, it seems, to changes in the way Invoice is structured.  

This pull requests resolves those failures, and also incorporates the version bumps from @farmdawgnation (https://github.com/agoel/stripe-scala/pull/14) and in fact bumps the versions further.