Fixed API RDocs, removed *_tpl from model exts
Added fixtures for Backends::Dummy
Minor version bump for rOCCI-core
Added basic impl for Backends::Dummy
Re-worked response rendering

Now renders into body or headers and without any
extensions for rOCCI-core
Updated Content-Type handling
Connected OcciModelController#index
Fixed Backends::Dummy configuration (fixtures_dir)
Updated specs