redirect users back to most recently viewed page after login

user story https://www.pivotaltracker.com/story/show/64997344
based on recommendations at the devise wiki
https://github.com/plataformatec/devise/wiki/How-To:-Redirect-back-to-current-page-after-sign-in,-sign-out,-sign-up,-update
with slight modifications to request paths that are ignored.
refactor of redirect after login

user story https://www.pivotaltracker.com/story/show/64997344
refactored store_location method so conditional logic in the
method has a much clearer intent based on code review suggestions
further refactor of redirect after login based on code review

user story https://www.pivotaltracker.com/story/show/64997344
tidied up matching line based on suggestion by @yarospace
refactored black_list method reduced to single method and used
rails route helpers to prevent hardcoding paths based on
comments by @yarospace and @yggie.
Addition of controller and view specs
redirect users back to most recently viewed page after login

user story https://www.pivotaltracker.com/story/show/64997344
based on recommendations at the devise wiki
https://github.com/plataformatec/devise/wiki/How-To:-Redirect-back-to-current-page-after-sign-in,-sign-out,-sign-up,-update
with slight modifications to request paths that are ignored.
refactor of redirect after login

user story https://www.pivotaltracker.com/story/show/64997344
refactored store_location method so conditional logic in the
method has a much clearer intent based on code review suggestions
Merge pull request #498 from PurityControl/user_redirect

redirect users back to most recently viewed page after login
Move ActsAsPage to a Model Concern
Remove Unnecessary Requires
Remove Pagination Search in Document model which was never used
Use proper constant naming in Event model
Fix Wrong Constant Name
Move the Pivotal Tracker Validator to a new lib/validators
Add Validators Directory to Autoloading Path
Add Spec for PivotalTracker Url Validator
Moving datetime extension from config/ to a core extension
Moved Uri Validator to the lib/validators/ directory
Moved spec for UriValidator to right place
Add Test to UriValidator
Add Indexes for References for better performance
Test for Article#url_for_me