URLRewriter (advanced) ruleset documenttype improvements

Even the (advanced) ruleset is currently very unintuitive, what should be changed IMO:

• In the conditions:
  • remove predefinded name
  • only show name field when required by the chosen type (header, attribute, cookie, parameter & session-attribute)
  • remove all the file, dir and nstanceof options from the operartor dropdown (would they work at all with Hippo?)