make changes according to last review
merge from upstream
merge from upstream/master, and resovle conflict
merge from upstream/master
wallet rpc api of wallet_dump_private_key, fixed #275
testing client rpc apis with simulated clients calling commands, and output the process as result
Merge pull request #276 from HackFisher/master

wallet_dump_private_key api and client rpc test, with some clean up to last review comments.