jinja2: fix broken filesizeformat filter

- details: https://github.com/mitsuhiko/jinja2/pull/59
speed improvements, added up-/down-rate and fixed list size option

- removed fetching of torrent file lists as this was
  really slow and the information wasn't used anyway; will
  maybe come back later in a torrent details view
- added global and per-torrent up-/download-rate information
- torrent list can be set to fixed size now
optimized configuration settings handling

- seperate input boxes for protocol, url and port in settings dialog
- basic qualification and verification for configuration settings
  - if no port is defined, assume 80 for http and 443 for https
  - if protocol is scgi, ignore username / password