Merge pull request #97 from habuma/master

Pass additional parameters (populated from preSignIn) when building OAuth URL in ProviderSignInController
Merge pull request #99 from habuma/master

Support 'state' parameter in OAuth 2 flow to protect against CSRF
Merge pull request #100 from habuma/master

Add in-memory connection repositories for testing and small-scale applications. SOCIAL-361
Merge pull request #101 from habuma/master

Fix findPrimaryConnection() to return null if no connection is found (SOCIAL-361)