Some cleanup of shared controller behavior and post controller spec
Various specs/features cleanups

 - PostsController-related features
 - UsersController features for access restriction
 - XPathology cleanups and refinements for xpath_for and simple_xpath_for
 - Navigating to page in features refactored
 - Resolving extraneous require/includes related to XPathology integration
 - Further usage of XPathology in view specs that did not
Fixing things that broke severely as a result of correcting the intended behavior in specs for /me access
[Fixes #46966513]
WIP, working state
Lots of refactoring, clean up of users_controller_spec
More refactoring