Merge tag '2.1.0' into develop

Final fixes for v.2.1.0  (2013-09-13)

  - Adds /source/log call
  - Updated /source/create call to comply with latest version of the API
  - Removed JSON gem - now dependant on Yajl-Ruby for JSON parsing
  - Added license info to gemspec
  - Fixed edge case when passing refresh token to authentication with G+ API
  - Fixed /source/get call
Use strip/reassignment instead of strip!
This prevents an error when username and api_key are command-line args
Allow versions of required gems to be bumped. Thanks for spotting this @Halloran
Fixed DPU example TypeError
Fix error using frozen string
Bump to v.2.1.1
Merge pull request #47 from datasift/2.1.1

2.1.1
Merge pull request #48 from datasift/develop

Develop