added channels_subscriber to factories
added channels_subscriber policy
migrated ChannelsSubscribersController to pundit :D
removed abilities related to channels_subscribers
removed cancan can? from user credits panel
removed can? from project update management (using pundit now)
fixed some spec descriptions
added channel policy
migrated channel profile controller to pundit
removed channel abilities from cancan
making scope simpler
Merge pull request #572 from diogob/migrate_channels_to_pundit

Migrate channels to pundit