allow to extend OAuthEntryPoint
Merge pull request #351 from evgeniy-baba/hotfixes/allow_extend_oauthentrypoint

allow to extend OAuthEntryPoint
Prepare release 0.2.7
Update DropboxResourceOwner.php to use oAuth2
Dropbox oauth2 test
Merge pull request #357 from adwww/master

Update Dropbox to oAuth2
Merge remote-tracking branch '0.2'
Add missing note about Dropbox changes
LinkedIn now uses OAuth2 approach
Merge pull request #353 from stloyd/feature/linkedin2

LinkedIn now uses OAuth2 approach
Added QQ and Sina Weibo
Merge pull request #356 from modi/cn

Added QQ and Sina Weibo
Add missing note about new resource owners (QQ & Sina Weibo)
Some cleanup of code:
- type-hint objects when possible,
- don't use container parameter in constructor
- reduce usage of container
- remove some code duplication
- made configuration a bit more readable
Refactor code to use Symfony OptionResolver component
Fix problem with twig extension after refactoring, cleanup after review