That's a change that spans 3 repos. Why don't I create a story to do that separately. 

This actually brings up an interesting problem for releasing plugins. Since they're just pulled from GitHub, we can't make changes on master that rely on an unreleased change to Mortar, then it'll break for everyone until the gem is updated.

Probably a good idea to bring back the notion of a dev branch, then release by merging to master.

Also what do you think about bring the notion of versions to plugins, as in make plugins require a `version.rb` in the root of the plugin?

It'd be really nice to detect whether an error originated from a plugin, then we can change the [styled_error](https://github.com/mortardata/mortar/blob/master/lib/mortar/helpers.rb#L366) function to display not only the current Mortar gem version, but also the plugin version if the error originated from the plugin, as well as change the submit issue link. 

Right now, I just copied the function from mortar helpers and altered it for watchtower. Thoughts?