Replaced Promptly with Inquirer

Note: Other than replacing the `!` check with a separate `Save changes to bower.json?` question, I did not refactor existing questions to take best advantage of Inquirer. I figured that could happen later with a new ticket that focuses on the UX of the prompts.

Example output:

![screen shot 2013-07-23 at 1 32 33 am](https://f.cloud.github.com/assets/51505/839818/4d52beb6-f359-11e2-9855-6ee1b276dd6b.png)

Fixes #645