Samples improvements

The part which I needed
to improve is the ApplicationBlock where I changed the OAuth2 classes'
structure a little and extended them with a lot of useful
functionality, like adding many Facebook and WindowsLive scopes,
fields, structures including the asked-by-many easy to use birthdate
and avatar url getters. I have also implemented the Google OAuth2
authentication and created one common interface for all 3 Graphs in
the code (which has the common properties like Id, FirstName,
LastName, etc.), so the authentication code became really simple if
you use my version of your ApplicationBlock.
Fixes StyleCop messages.
Merges András Fuchs enhancements to the OAuth samples.