Support for Altcoins

[theemstra]

Hi Jayco!

Thanks for your work!
Do you think it'd be possible to add support for altcoins like Litecoin, Ethereum, Dash, NovaCoin, DogeCoin, Gulden, Peercoin etc?
The same framework could be used, for example, when checking, the prefix bytes of wallet addresses are different, so are the labels/names for coins. For example DogeCoin uses MDoge etc.

[tenfef]

@theemstra Open to pull requests to add these features. Shouldn't be too hard :)
I only need BTC for my needs.