first pass of signing

[alexpeterson91]

fixes #32

[alexpeterson91]

@mgarciate
Ok so upon testing further and reading the Pokt docs more, it doesn't seem there is an official way to use Pocket to sign an arbitrary message, it seems only able to sign specially encoded hex data likely ed25519, the pocket wallet address hash algorithm.

Errors as follows: changing the values for the account address's from the signing function. pocket accounts sign <account address> "account address" details and source

encoding/hex: invalid byte: U+006B 'k'
Address Error Incorrect address length4bc8b928ef53
Address Error encoding/hex: odd length hex string4bc8b928ef53

Seems we need to simplify this a bit and just have it self sign the account address no need to add a new input field, at least until we implement non-custodial staking #23