Build a minified asset as well.

In one of the build system refactors, we stopped building a minified
asset. This restores the built minified asset when running
`make dist`.
Install broccoli-cli for CI.
Bump broccoli-uglify-js to 0.1.2.

This includes a patch that calls `Filter`'s constructor (essentially
calling `super` on the parent class) to initialize options,
specifically `targetExtension`.
Merge pull request #85 from zendesk/josh/build-minified-asset

Build a minified asset as well.