added PreviewServerCommand
implemented simple websocket receiver
Merge branch 'develop' of git://github.com/sulu-cmf/SuluContentBundle into feature/preview-splitscreen
added basic functionality preview service
added preview test
return only rdfa defined part of html
added stopPreview method
created basic files for preview controller
updated preview service and added render action
added invoke controller to preview
refactered preview, fixed tests
refactored preview interface
implemented simple preview controller
render preview template
implemented simple polling
include javascript in reder process
fixed tests
added todo
added icon to start preview
updated urls