Return 422 instead of 500 when handling body

Using a 4xx error would be more appropriate for this since the server is parsing the content from the client and needs to let the client know the data is malformed (not the actual HTTP request but i.e. JSON semantics). The definition for 422 is described in [RFC 4918](https://tools.ietf.org/html/rfc4918#section-11.2)
add patch support to cowboy_rest
Fix chunked streaming of request body and improve speed
Merge branch 'rest_patch' of https://github.com/treetopllc/cowboy
allow POST rest handling to specify path after accepting content
Makefile verbosity tweaks
Merge branch 'rest_post_created_path' of https://github.com/treetopllc/cowboy
Implement authorization header parsing

Basic HTTP authorization according to RFC 2617 is implemented.
Added an example of its usage with REST handler.
Merge branch 'feature_basic_auth' of https://github.com/ivlis/cowboy
Merge branch 'patch-1' of https://github.com/CamShaft/cowboy

Conflicts:
	src/cowboy_rest.erl
add websocket example
Merge branch 'websocket-example' of https://github.com/pvieytes/cowboy
Fix a new warning found by Dialyzer R16A
Fix small error in the websocket chapter in the guide

Reported by Michel Rijnders.
Small routing guide fix

Make cowboy_router:compile/1 return to be consistent with current
implementation.
Merge branch 'fix_routing_guide' of https://github.com/ivlis/cowboy
Rename example 'static' to 'static_world' to avoid confusion
Make sure the peer name is always available