deprecate eth_pendingTransaction since it only applies to local accounts

[meowsbits]

eth_pendingTransactions returns the transactions that are pending in the transaction pool and have a from address that is one of the accounts this node manages.

Rel #91 (comment)

[BelfordZ]

I didn't know it was just the accounts managed by this node... that's wack.

if that is the case, then it makes sense to me to deprecate it. Banish all things related to eth accounts.