Fix mst.py, include profiling data

The profiler is line_profiler (1.0b3) on python2.7

Timings:
  -3635748
  edges500.txt  0.06s user 0.01s system 99% cpu 0.065 total

  -4879008
  edges500dense.txt  0.33s user 0.01s system 99% cpu 0.335 total

  -8579081
  edges1000.txt  0.13s user 0.01s system 99% cpu 0.141 total

  -19868036
  edges2000dense.txt  6.40s user 0.10s system 99% cpu 6.505 total

Signed-off-by: Andrew Tselischev <andrewtselischev@gmail.com>