Rename specs to remove MessageTask dependency

Is there a need to keep both the feature spec and the Ember integration
spec?
MessageTask be gone
Add migration:
 - Changes MessageTasks to AdHocTasks
 - Removes MessageTask as an option to create tasks/task-templates
Fix task creation

TaskFactory actually puts the ‘role’ on a task, so it can’t be removed
completely (yet).
Upcase SQL keywords
remove unneeded method
Update Ruby
Merge pull request #645 from Tahi-project/remove-message-task

Remove message task