Add scale control

Add a scale slider to control the scale passed to the SegmentTubes CLI.
This slider can be linked with the seed display size.

The scale isn't associated with each seed. Instead, whenever the CLI runs,
it uses the current scale.
Bump TubeTK to get SegmentTubes scale fix
Add parameter file to Interactive Segment Tubes

The parameter file can either be selected from the default parameter files
present in the parameter file resource dir or loaded directly from file.

Solves Issue #6
Bump TubeTK to revert scale change
Hide seed status by default

Solves Issue #16
Merge branch 'InteractiveSegmentTubes-Scale'

* InteractiveSegmentTubes-Scale:
  Hide seed status by default
  Bump TubeTK to revert scale change
  Add parameter file to Interactive Segment Tubes
  Bump TubeTK to get SegmentTubes scale fix
  Add scale control
BUMP slicer and TubeTK

Bumped slicer to use the --launcher-show-set-environment-commands
Bumped TubeTK for segment tubes and merge adjacent images fix
Bump TubTK so VesselView works with the latest TubeTK-experiments scripts