Add section for deprecated selectors

This lints all active packages for deprecated selectors using [atom-selector-linter](https://github.com/atom/atom-selector-linter). Currently, linting runs when you open the deprecation cop view, or whenever you click 'Refresh' on the selector section.

![screen shot 2014-11-12 at 2 30 59 pm](https://cloud.githubusercontent.com/assets/326587/5019934/acd748a6-6a78-11e4-87da-ccaac2400c75.png)

Remaining tasks:
* [x] Profile linting with more packages installed
* [x] Add linting for all selectors identified in atom/atom#4045
* [ ] Add deprecated selector count to the status bar view
You could just load this package by path I believe, like

```coffee
atom.packages.loadPackage(fakePackageDir)`
```