Improve input args for deployment / transact

[cducrest]

The cli tool takes input arguments for example for arguments of the constructor of a contract or to interact with a contract. It seems there is no way currently to provide empty arrays as arguments. This should be improved for example by using a json string.

A function that uses input args: https://github.com/trustlines-protocol/contract-deploy-tools/blob/master/src/deploy_tools/cli.py#L354

The function that processes the args: https://github.com/trustlines-protocol/contract-deploy-tools/blob/master/src/deploy_tools/cli.py#L622