Cumulative v3.0.0 commit.

+ Large general cleanup

+ Don't store metadata on 404 response upstream

+ Add .jshintrc

+ Allow a blacklist of packages via a JSON configuration file ( --package_blacklist <file path> )

+ Allow stale resources to be served while the upstream registry is unavailable.

+ Other minor fixes

v3.0.0 release
Add .travis.yml
Dummy travis-force-build commit.
Require node 0.10 or greater.
Add Travis-CI badge.