Add content negotiation for API calls with 'full' result format

- Return different RDF serializations depending on 'Accept' header
- Add tests with 'Accept' headers for different RDF serializations
- Update index page with basic documentation on content negotiation
Add Scala project nature for IDE support in routes and templates
Update to Play 2.1.1 (config files, content negotiation API)
Automatically insert supported accept headers into index page
Merge pull request #41 from fsteeg/content-negotiation

Add content negotiation for API calls with 'full' result format