Invalid Facebook client id and secret produces obscure errors

[ryanjbaxter]

If you try to use facebook to login and you have an invalid client id or secret we do not handle the error very well. Basically the response looks like it has error json in it that we don't catch early on until we try to parse the query parameters. We should be looking for this error json early on and handling the error appropriately.

[kehphin]

Fixed this today, will submit a pull request for this after the code review changes of the current pull request