refactor: Removed extra code from Manage handler
refactor: Removed extra code from Manage handler

Removed user = self.user from Manage handler
and replaces all occurrences with self.user
to reduce complexity.

tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO,tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO,tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO