create requestResponse module

The requestResponse module is used for decoupling Backbone and
Backbone.Marionette application modules regarding Request/Response
pattern.
introduce paths helper module
add request/response handler for projectDirectory
fix for 095e5d11d0
apply the request for project Directory to get the absolute path of a picture
introducing the event of selecting a picture
move background view to the right directory
rename joinPaths to join in Paths file
use dahufile URL protocol
create workspace's screen view
setup click event on filmstrip screens'
display workspace view
update workspace view onPictureSelect event
capture and handle model change
cleanup

- delete unnecessary dependencies
- remove useless debug log
change event namespace and rename event
skip rendering of non-background object
reset stylesheet
initial dahuapp stylesheet
clean dahuapp main layout and add toolbar