suggestions for running option

Hi, I'm using this network and I think It would be better if there's more options on running network.

1. init flag
* if this flag is true, run `init_indy_keys`.
* when I specify the `IPS` argument, I need to change the commented part on `von_generate_transactions` file.
2. update `initEnv` funcion on `manage` file.
* I fixed `initEnv` function since I'm too lazy to put every arguments on a commend when I try to run the network.
* I've just moved down the part that parses env variables on `.env` file.

Review von_generate_transactions for the commented IPS-related section and manage for initEnv. Confirm how the proposed init flag should invoke init_indy_keys and how environment variables are currently parsed. Done means the network can accept the requested running options without manual edits or repeatedly supplying every argument.

Written by the indexing model from the issue text.