added translation for grey
add Kwf_Rest_Controller for implementing custom rest controllers
improve json error output

- always output error string (to be consistent dev/prod)
- also show message if exists
switch to json output by defining jsonOutput param

this allows output of json in error controller for rest controllers
set jsonOutput param in viewRenderer helper

required because we need to access it in viewRenderer and preDispatch in controller is too late
controller: improve json output

- never output html (use eg. postman for debugging plus benchmarklog if you need benchmark data)
- output correct http response code
- always output exception message as error (this should not contain secret information - hopefully)
default exception messages for NotFound and AccessDenied

required as we output this msg in ErrorHandler for json requests
Bugfix continous playing video in iframe
- store iframe variables in data and remove / create iframe dynamicly
fix creating cssClass if kwf path looks similar as web path