updated for rails4
Fix rspec depreciation warning
Rails4 compatibility
Update travis to test only against rails4 and ruby 1.9.3/2.0.0
Fix failing mongodb test by destroying record (to prevent same id insert)
Compatibility with rails 4.1
Upgrade appraisal gem
Remove Rails 3.x support
Upgrade to RSpec 3
Update tests for RSpec 3
Move away from RSpec .should syntax
Fix tests for new version of mongo_mapper
Fix tests and deprecation warnings under Rails 4.1
Add Code Climate badge