Fix error display w/o session.

Fix display of errors w/o a valid session by:
  * wrapping @css[:background_color] into css_background_color,
  * adding rescue to role_allows.
Fix: session[:last_trans_time] was not set.

session[:last_trans_time] is not set in the login request but later.
We need to anticipate this in the PrivilegeCheckerService.
Add tests for referer checking on requests.
Refactor and cleanup validate_user in DashboardController.
Simplify set_user_time_zone.
Simplify ie8_safe_redirect calls.
RBAC: refactor and remove fallback.
Fix small issues in English locales.

Remove spaces at the end of line.
Fix one key.
Fix a typo.
validate_user: fixes and tests.
Fix specs according to Rubocop complaints and review comments.
Fix specs after RBAC refactoring.
ApplicationController: better name for a method.
Split and simplify method validate_user.
Fix dashboard_controller specs after rebase.
Disable Utilization button for Instance if C&U data is not collected

 https://bugzilla.redhat.com/show_bug.cgi?id=1127009
Added a new entry for Automate Explorer in miq_shortcuts.yml

This will add Automate Explorer as a startup page.

https://bugzilla.redhat.com/show_bug.cgi?id=1129113
Update Gemfile.lock for newer appliance.

https://bugzilla.redhat.com/show_bug.cgi?id=1142316

[skip ci]
Corrected typo

https://bugzilla.redhat.com/show_bug.cgi?id=1141203
Merge pull request #643 from bmclaughlin/correct-listnav-typo

Corrected typo
Merge pull request #153 from martinpovolny/rbac_cleanup

rbac cleanup