Remove facebook comments integration

[kohsah]

Facebook comments integration needs to be completely removed at configuration level.
Ideally, it needs to be driven by configuration. A flag set at build time should enable the facebook comments integration. NOTE: this could imply having a derived package.json which does not include facebook related packages, and the regular one that includes the packages.

[kohsah]

Update:
Inlcude facebook in the build, but load it / enable it at runtime based on a flag set in the user profile.
For anonymous users facebook integration will always be disabled.
For logged in users, the facebook integration will be enabled based on a flag set in the user profile configuration.