Revert "removed a debug logging call; return early from is_signup() if we already have the value of $this->is_signup"

This reverts commit 3e75ce50dd08fc4a6482b1a4895cff7c42bb4a97.
Revert "added a function to check if we're on the configured sign-up page or not"

This reverts commit d0c1156b52ad2b65eb4a7657b925cd81122c82b3.
Merge pull request #22 from wluo/github-4055

reverted the is_signup() function