Miscellaneous repo cleanup

- Cleaned up package.json
- Cleaned up bower.json
- Cleaned up wording, fixed broken links, and improved contribution
instructions in README.md
- Removed grunt-cli as a dependency in .travis.yml
Oh wow, I didn't know about that comment hack. That's terrifying.

The reason I set private to true is because we currently don't have an npm module for firebase-simple-login and that is an easy way to make sure we don't accidentally publish it. No other reason really. I have a task to publish it on npm and make it work with browserify, but that may not be done by the time we merge all of this code into the Firebase client.

I'll add a comment explaining why it is `"private": true` in my next check-in