Merge pull request #3 from inhies/f.cleanup

F.cleanup
* development: (21 commits)
  Add USSD support, split in to multiple files
  Start splitting code up logically
  Create Account type
  AccountBalance can be a function-local type
  Rename New to NewFromAPI()
  Add check for client reference length
  More descriptive test messages
  Add apiRoot constant
  Add TODO for rate limiting
  Limit API requests to 1 per second
  Add NEXMO_FROM env var
  Provide more useful error output on message tests
  Use build tags for tests
  Rename NexmoWithApiAndKey
  Cleanup sendMessage()
  Remove erroneous comment
  Wrap lines at 80 characters
  Update README.md
  Use enviroment variables to store testing credentials
  Rename package to nexmo
  ...
Merge branch 'master' of https://github.com/inhies/gonexmo
Updated comments and README to reflect recent changes.
Fixed some comment style / semantic style issues.
* development:
  Updated to google style API package
  Create SMS type and move Message methods there
  Create Account and Message types
Merged in new structure.
Merging is not always simple... :)
* development:
  Add ability to handle inbound messages
  Remove comm file
Merge branch 'master' of github.com:njern/gonexmo

* 'master' of github.com:njern/gonexmo:
  Merging is not always simple... :)
  Fixed some comment style / semantic style issues.
  Updated comments and README to reflect recent changes.