Module deprecation missing on VM

[evgueni-ovtchinnikov]

Running ctest on VM got no module named deprecation error. Had to do sudo pip istall deprecation.

[KrisThielemans]

This is a VM issue. Please file in approriate place.

However, this has been addressed by @paskino in SyneRBI/SyneRBI_VM#143. I believe I also asked to put this in our installation instructions. Not sure if that happened.

More worrying is why we need it.

[rijobro]

Apologies, I added it in #497, where I wanted to deprecate process in favour of forward/back/direct/adjoint. I can remove it if it's causing too much hassle.

[KrisThielemans]

if it serves a purposes, it's fine of course. Should be added to our list of required Python modules.

I suggest we do that by addressing #124. Seems a 5 minute job to copy the list into that file. Then in the install instructions we just link to the file. Later on, in the VM, we use it to pip install.

[evgueni-ovtchinnikov]

VM now has deprecation, so closing the issue