[webui] small test case that bento can be setup (and fix it)

remove also references to mobile_views and validate_xhtml - I still like to have
our pages to be valid HTML, but it's much harder with HTML5
[webui] do not reuse Thread.current's user in user#login - it's reused
[webui] move helper functions used by controller to model
[webui] fix test suite
[webui] Bring back :service mapping for activexml for remote add_file
[webui] add test case for 'remove file'

(and move the functionality in the package model)
[webui] remove dead service model code
[webui] remove the rest of the engine

also make sure the API routes to not try to reply to HTML - which only
gives crashes