* Brainstorm fix for expired ID token issue.
* Only retry once, in case of clock skew, and fix unit tests.
* Fix FIRAuthTests.
* Modify check to be for if the token will expire within 5 minutes.
* Update changelog.
* Add debug logging around token expiration.
* Use FIRLogger instead of NSLog.
* Move log statement.
* Add another log statement when access token is updated.