New luigi task status and graph visualiser (squashed for cleaner history, including commits by lallea, Anders Nyman and Uldis Barbans)
New hand-written layout engine more suited to directed acyclic graphs (like dependency graphs). Backend unit tests now use scheduler directly instead of RPC.
Killed old visualiser and fixed 2.7-dependent tests
Visualiser now fetched error traces from luigi. Failed nodes in graph are clickable for a traceback. Ships with mock data for testing UI in isolation
Added root path handler to redirect / to /static/visualiser/index.html
Merge pull request #80 from DavW/new-visualiser

New visualiser to display failing tasks and dependency graphs