Merge pull request #39 from keizof/master

Make SqlServerConfig and SqlCeConfig public
reorg for samples
add helper to get application url from httpcontext
use new helper for app url
add missing reference
add missing reference
first stab at implementing linked accounts
refactoring/cleanup on account linking
more cleanup to linked account code
remove unused dependency
move account verified and login allowed checks to base SignIn implementation
reworking DB entities so linked accounts get deleted when account is deleted
change ctors to protected internal
add dispose
fix tests
add some comments
scope linked account to tenant
rework to accomodate changed Guid ID type
rework repository semantics to better allow for nosql style semantics