[ui] Added a custom_handler named StaticFileHandler

+ To support directory listing because owtf relies on that ability to show files generated by a tool
+ Torndao doesn't support it natively as of now
[plugins] Changing the paths relative to targets output folder so that

+ Easy to export the results from machine to machine
+ Better not to hardcode full paths
+ Less revealing info so users can submit bug reports (I am skeptical)