Merge branch 'cf' into 'master'

[install/from-scratch] dont pin on versions. use conda-forge

Fixes #26 also adds caffe and tensorflow.
The script now deletes the old env to make sure the new env is cleanly created.

This will install a broken caffe right now which I am trying to fix here: https://github.com/conda-forge/caffe-feedstock/pull/20

See merge request !17