Add facebook channel file.

Not sure where ths belongs in the rails hierarchy; for now have put it
at the top level and changed the path in facebook-login.js
accordingly.
Remove log file.

Added it to repo by accident when I added all the rails stuff.
Get facebook api loading correctly.

Moved the fb-root and the load of the facebook-login.js to the top of
the body so it can load in the place that it suggests. The facebook
login button now appears in the modal dialogue and will log you in.

NOTE! you must add an app id to the login structure at least once
during the current sesseion before facebook's stuff will load, which
also involves pointing that app's site URL to your website (in this
test case http://localhost:3000 works just fine). So it all works
contingent on that; I just don't want to commit the app id number.
Misc comment commit.