Added OAuth support to Gutterball's API

Created from PR #747 against master as gutterball-hibernate branch was merged into master.

- OAuth functionality can be disabled via configuration
- OAuth consumers are added via configuration; similar in format
  to Candlepin's implementation.
- Moved CustomSigner, SecurityHole and RestEasyOAuthMessage from
  server to common
- Added OAuthInterceptor to Gutterball
- Updated the buildfile accordingly
- Added unit and spec tests
Right, but I guess what I'm getting at is, without having at least one consumer/secret setup when gutterball is started, then you can't access anything that is protected -- noting configured to check against. To me, that is a configuration issue, and I would prefer to be told early that something is wrong.

I'm not sure what the point of allowing gutterball to start up, if it is not configured correctly.

If you feel strongly against this, just warn. I'm Ok with that. It is really just a matter of opinion.