Adds new context caching system

- Reduces allocation overhead
- Reduces Garbage Collection stress
- Reduces memory fragmentation
Adds NewWithConfig() and CacheStress()
Adds Keep() and Release() to gin.Context
Added support for OPTIONS verb
Added OPTIONS to README
Testing Copy() instead of Keep() and Release()
Improves Copy() in gin.Context
Merge branch 'contextCaching' into develop
Merge branch 'options' of https://github.com/alexandernyquist/gin into alexandernyquist-options
Adds HEAD
Some work around bindings. it may do not compile
Setting Get metadata method to return both an interface as well as an error to remove panic.
Fixes wrap around http.ResponseWriter
Merge branch 'master' into develop
Fixes "http: multiple response.WriteHeader calls" in 404 [Issue #29]
Adding MustGet method. Updating README.
Better logger

 - Includes http method
 - Includes coloured status code
 - Better formatting
Do not update status code in Abort() if code is a negative number
Adds a console image
Nicer BasicAuth API