Working on content type negotiation API
Fixes Content.Negotiate API
Better errors in Context.Negotiation
Add response body size to writer interface
Fixes responseWriter.Size()

- "written" boolean is not longer needed
- size is reseted
- addition instead of assignation
Removing exclamation marks in Go.
(feature)add http method log-color,like http response status code
Adds API for interrogating current mode

It returns one of the following values:
- gin.	DebugMode
- gin.	ReleaseMode
- gin.	TestMode
change %4s to %-7s for align
Merge branch 'master' of github.com:se77en/gin into develop
Enables colored tag for http method in gin.Logger()
Merge branch 'negotiation' into develop
Updates logger screenshot
Adds logger source code
Added support multipart/form-data #109