Adds documentation and slight refactoring to Http

- Moves GC method `clean!` from callback to below blocking loop in `process_client`
- Adds explicit types to `WebsocketInterface` methods
- Verbose documentation
Reformats documentation to 80 char width.
Document Httplib.jl
Merge branch 'doc1' of https://github.com/hackerschool/webstack.jl into doc1