Added basic queuing

Torrents must be managed for queuing to work, for example, a torrent started or stopped manually by the user won't be started automatically.
Currently you can only limit the number of simultaneous downloads/seeds.

Also escaped the path to open the file.
Forgot to remove a shitty line*
Fixed some problems with queuing and added status
Merge pull request #110 from gtorrent/wip/queuing

Adds queuing