Add Facebook Feature: Add Metadata Tags for Classifications from Facebook

[shaunanoordin]

Facebook Feature Update.
Required functionality for Minimum Viable Product.

NOTE: This is specific for the User Story wherein the user accesses Galaxy Zoo from Facebook. i.e. this assumes that the user is logged into Facebook, and proceeds to access Galaxy Zoo as a Facebook App.

• When a FB-logged user makes a classification in the Galaxy Zoo FB App, the classification MUST be marked with metadata indicating that the user was logged in from Facebook.

To Discuss:

• Are there any other occasions where we would be interested if a user is logged into FB? For example, would it matter if a user is logged into FB, but then goes directly to galaxyzoo.org instead of the Galaxy Zoo FB App? (My thoughts are nope, no, not at all, but feel free to dispute this.)