RPC Args

* CALLDATA use getData
* removed old context get range value
* removed casting big => int for some cases
* pc now big int #457

Minor fix

Update README.md

Update README.md

settable etherbase

Use ExtraDB for RPC storage. Fixes #577

Update response types + tests

- etherbase flag for block reward destination
- coinbase => etherbase
- CLI- eth Config -> eth, xeth -> RPC / Miner
- use primary instead of coinbase as the unlock magic wildcard
- accounts: firstAddr/Coinbase -> Primary

Rename ethereum executable to geth

Conflicts:
	rpc/args.go

import/export accounts