Set up travis and add some fancy badges in README

Steps needed to enable travis:

- Go to http://travis-ci.org and create an account.
- Github oAuth flow
- Open settings for your user, activate travis for One-com/assetgraph
- https://travis-ci.org/profile/papandreou/profile and cop the Token
- Use the token to set up the travis service hook for the GitHub assetgraph repository

Closes #119