Merge pull request #486 from makaroni4/master

FIX bug with add_provider_to_user and authentication class in CamelCase
Fixing specs in master
Merge pull request #487 from ognevsky/fixing-specs

Fixing specs in master
Use actual rails version
Merge pull request #488 from ognevsky/use-actual-rails-version

Use actual rails version
Providers refactoring
Gem tasks in Rakefile
Updates about Rails 4 status
Merge pull request #484 from ognevsky/refactor-providers

Burn and resurrection of external providers
Add initial DataMapper support
Datamapper support improvements, passing tests
Add DataMapper Support
Add datamapper to travis.yml
Update README, remove dm-types require from submodule
Remove dm adapters redis, sqlite from gemfile and code cleanup
Overwrite save methods in DM adapter
Use sorcery_save for saving
Update DataMapper specs
Add exclude filter for datamapper
remove test helper empty module