capistrano role task grouped in one namespace
Re-added old role tasks names for backwards compatibility

This is for pull request #249
Cleaner aliased rubber role tasks
Make capistrano role tasks available

WIthout allow_optional_tasks, required_task doesn't do anything
Show options in list of roles after rubber:roles:add
Merge pull request #262 from magoosh/group_role_tasks

Group capistrano role tasks in one namespace (without breaking compatibility)