Make tagpool metadata mandatory and add methods for checking what functionality a channel supports.
Add check for channels that support generic sends to send survey action.
Merge branch 'develop-frontend' into feature/issue-497-better-logic-for-enabling-send-message-and-survey-actions
Have get_channels also retrieve tagpool metadata.
Add utility methods for attaching a channel to a conversation in tests.
Disable bulk send action when a bulk send conversation has no suitable channels attached.
Attach channels to survey conversation tests that need them.
Attach channels to bulk_message send action tests and add a test that the action is disabled if no suitable channel is attached.
Replace attach_channel() generic helper functionality in setup_conversation().
Fix with_channel support in setup_conversation (we were trying to add a channel before the converation had been created).
Add generic supports() function to channel model.
Add helper method for adding tags to a conversation and creating tagpools with specificed metadata.
Add has_channel_supporting(...) helper method that checks whether any channel called by get_channels() supports the specified properties.
Use has_channel_supporting() to check whether a send actions should be disabled or not.
Add TODO about fixing the structure of our test helpers.
Merge branch 'feature/issue-497-better-logic-for-enabling-send-message-and-survey-actions' into develop-frontend