Use Bower to manage third-party front-end dependencies

This pull request switches to using Bower to install dependencies.

Most of the libraries Doppio uses are available from Bower, however there are a couple of issues:
- [ ] Changes have been made to the jQuery console plugin, so these patches would need to be merged into the repo before it can be installed from there. Alternatively, another console library could be used (see #143).
- [ ] The Google Closure library is hosted on Google Code, so `gLong.js` can't be installed from Bower. Depending on the license, we could make a shim repo to fix this.

Libraries that are on Bower that still need to be included in the manifest:
- [ ] Ace Editor.
- [ ] Twitter Bootstrap.

Now that BrowserFS is packaged up as a library, we can register it on Bower and install that too.

Once all these issues have been solved the entire of `vendor/` can be removed from version control, reducing the repo size and simplifying `.gitignore`