Add db and web service support for lane tags.
Clone tags when cloning a lane.
Add support for selecting the lanes to show by tags in index.aspx

For now it's hidden away and you'll have to edit the url to filter
by tags (index.aspx?tags=tag1,tag2,etc)
Lane dependencies are never fulfilled until the revision has completed.

This fixes a bug where a dependent lane would end up getting scheduled
as soon as a step failed (with issues) in the dependency lane.
Refactor a bit to make reduce future code duplication.
Implement index view based on tagged lanes.
List the available tags as a second top-level entry in the left menu.
Remove dead code.
Handle any exceptions when fetching the data for the tree view.
Merge branch 'tagged-lanes'.
Add a timer to detect if a test run is stuck.
Make the 'no output for X minutes' timeout configurable.
Don't give/assign work to disabled hosts.