v0.0.4-unstable

1. change timeout of download request, pullrequest #23
2. sign content add from, pullrequest #24
3. receiptroot calc bug, pullrequest #25
4. feature genesis bootnodes , pullrequest #26
5. reduce event's mutex competition, pullrequest #27
6. fix receipts root different err, pullrequest #28
7. testnet genesis.json, pullrequest #29, pullrequest #31 pullrequest #35
8. update consensus/miner/work, pullrequest #30
9. update readme.md , pullrequest #32
10. multi bonus, pullrequest #33
11. return right gas when trasfer internal tx , pullrequest #36
12. add some functionality for wallet and blockchain broswer, pullrequest #40
13. change env script, pullrequest #41
14. bug miner private checke, pullrequest #42