Contextual Facepalming

I laughed for a good ten minutes when I saw this get published... and then I decided that I just had to link it up to @tombell's excellent [test-status](https://github.com/tombell/test-status) package. So, here's a pull request that accomplishes just that. While your tests are failing, Atom expresses its displeasure!

![contextual-facepalm](https://cloud.githubusercontent.com/assets/17565/2574960/700e2378-b942-11e3-964e-390f2941e8d0.gif)

Actually, it's a little more flexible than that; it lets you specify any set of events that will trigger the facepalm, and any set that will turn it off again. If the activation events are empty (as is the default), every editor will be facepalming as they do now. If you specify deactivation events but no activation events, all editors will *start* facepalming but turn off when a deactivation event happens.

I did need to change the package name in `package.json` while I did this, which will probably break `apm publish`. :unamused: Sorry about that, but if I didn't, `npm` broke and I couldn't add [emissary](https://github.com/atom/emissary) as a dependency for the event management stuff.