Add create account and sign functions

[treeder]

web3 account create => generates an account and prints the address and private key
web3 sign "some data" => [this](https://web3js.readthedocs.io/en/1.0/web3-eth-accounts.html#sign)

Hopefully without importing these functions from main gochain repo, probably better vice versa.

• [x] web3 account create
• [ ] web3 sign DATA