Modify Python notebooks to allow execution in Binder

[carshadi]

• add environment.yml
• initialize pyimagej through the Fiji gateway
  • N.B. the notebook will only be able to run to completion once the scijava branch is merged to master.
• remove all paths to local machine

Convex hull notebook on mybinder.org example https://mybinder.org/v2/gh/carshadi/Simple_Neurite_Tracer/scijava?filepath=%2Fnotebooks%2Fconvex_hull.ipynb

[tferr]

Amazing @carshadi ! This is simply the most awesome of all the additions to SNT!

[carshadi]

all credit should go to pyimagej developers!