Add option to set the coin type

[Thoralf-M]

Description

When creating the first account one should be able to set the coin type

Motivation

The private tangle uses a mnemonic with IOTA coin type as default, if one would use the same mnemonic, one would still not be able to access the funds, because the cli wallet uses another coin type as default

Requirements

1. Add optional coin type parameter

Are you planning to do it yourself in a pull request?

Maybe.