Integrate proof generation tool with truffle exec

[abhayks1]

Context

In Proof generation tool, generator.js is written as series of truffle tests i.e. it's. However it doesn't test anything(no asserts). Reason is contract deployment uses truffle artifacts and truffle network configuration for connecting to geth. Truffle artifacts objects are only accessible through truffle framework.

Proposal

• Integrate truffle exec with proof generator to have access to contracts (artifacts) and Web3 as per truffle config.

• Remove all the describe/it's from generator.js. Generator should look like tool than series of it's.

• Please check https://truffleframework.com/docs/truffle/reference/truffle-commands#exec and generally the truffle documentation.

Discussion Reference
#717 (comment)
#717

cc: @schemar @benjaminbollen