Resource#fetch() works on an individual URL.
Resource#fetch handles URL paths; Null URL ok.
Adopting Backbone.js's extend method.
Tweaked Resource extend usage.
Collection parses its own fetched data.
Enforcing Collection contains only Resources.
Merge branch 'feature/resource-fetch' into develop
Version bump.

Closes #5. Resource collections
Closes #6. Resources and collections can be fetched from remote services and parsed.
Added some docs.
Merge branch 'release/0.0.8' into develop