Add support for browser field in package.json

Based on the unofficial spec
https://gist.github.com/defunctzombie/4339901
Map false to a blank module
Add tests for browser field handling in npm metadata
First sketch of the tests for createMapper
Add author to blank and createMapper
Normalize the modules in browser map based on the package root
Stop fetching `package.json` for bower, make `bower.json` optional
Fetch package.json for bower components, but ignore dependencies
Default to "0.0.0" version if bower.json contains no version

This is important, because bower is considering making the version
attribute in bower.json optional. But rave needs a version to be able
to correctly normalize package ids.
Add a comment about falling back to package.json
Don't use the versioned uids in the mapper
If no bower.json or package.json exists - fabricate the meta
Mention rave REPL-like commands.
Reword blurb about rave being a part of cujojs.
Move the uid parsing logic into createPackageMapper module
Improve npm cralwer browser field tests
Rename moduleName to name
Make uid.getName handle both module uids and names
Rebuild rave
Prioritize Rave Starters over starting "from scratch".