adding basic bower support

This solution is far from optimal, as it hardcodes the package manifest location to `bower.json`.  Also, many people do not keep much information in bower configs since they usually contain a `package.json` in the same project.

However, this will at least work for some packages consumed by Bower, and gives us a starting point for further extension.

Thankfully, it was an easy add after the work done with NPM.  :)

Now if only Bower didn't hijack `stderr` to display verbose logging information...