* rename Bind to BindMiddleware
* make things private
* removed unused part of data bindings
* provide json and form binding helpers
* add example of binding migration in login api
* implement validation
* fix tests
* remove debug output
* put new bind api into macaron pacakge
* revert bind api breaking change
* pass url parameters through context.Context
* fix url param names without colon prefix
* change context params to vars
* replace url vars in tests using new api
* rename vars to params
* add some comments
* rename seturlvars to seturlparams