Improve the management of files

[AntoineRondelet]

For now the proof.json, vk.json, proof.raw and vk.raw are written at hardcoded path.
This makes usability pretty bad, and generates files where it shouldn't.
Using environment variables, and adding the path to the files as arguments of the functions generating the proof and the setup would be better

[barryWhiteHat]

Yes this is a good idea. Its currently very messy how files are written. There is a bunch of other python clean ups that could be done also. Splitting snarkWrapper/deploy.py into a script to deploy the contract and interact with it and a python script to interact with libsnark. Also changing the way that imports happen. Currently i do a messy hack

import sys
sys.path.insert(0, '../snarkWrapper')

Which is not very nice. and probably not the python way to do this.