Made SignInCommand use idps from options.
- Removed SignInCommand's dependency on IdentityProvider.ActiveIdentityProviders.
- Added a new IdentityProviderDictionary class which is much more simple than ActiveIdentityProvidersMap.
Added missing XML comments on IdentityProvider.
- Just added for those parts that will remain after I'm done with the config handling changes.
Removed AcsCommand's dependency on IdentityProvider.ActiveIdentityPRoviders.
- Now reads the idp info from the supplied options.
- Added XML doc to IdentityProviderDictionary.