move trace report

[al-niessner]

The trace report should be moved out of archiving. It should be an "under construction" page until updated manually from outside the pipeline. It should return to "under construction" at every restart.

[al-niessner]

The intent of the trace report is to show which targets have done what path and/or some portion of the path. There are now 1000 targets and plots are meaningless. Also there are errors:

1. len(at) gives all nodes not just roots while for x in at'is just roots. Resolve by changing trace.py to know this or fix at to return number of roots? Supposedly, at is a list of nodes so it should match. May be a deeper problem.
2. Plots should be more helpful in allowing selection of targets maybe. Can bokeh support such a plot?