Remove all erlang files

merge
Start Elixir API
Fix IO related functions, add conditional `Accept`/`Content-Type`

+ Add marshalling by content-type
+ Add test examples
Minor fixes to Marshaller:

+ Set JSON to default marshaller
+ Improved code formating
+ Remove YAML marshaller
+ Proxy JSON marshaller to allow empty response bodies
Fix correct termination of request
Rename module attributes (accepts, provides) -> (consume, provide)
Fix unused variable warnings
Add CORS and log middleware
Remove unecassery Accept header
Use JSX infavour of elixir-json