devel/rubygem-devise: switch to Rails 4 and fix fallout
Remove support of Rails 3 since we are obsoleting this version from the
ports-tree. This fixes the fallout-message to ruby@.
Also DEPRECATE rubygem-devise-rails4 in favor of rubygem-devise
and adjust dependencies of security/rubygem-devise-two-factor and
www/gitlab.
Approved by: pi (mentor)