remove watch from service_mgr
fix error log
avoid issue #154
fix issue #156
1. 增加一个错误输出
improve seri lib
clear socket when connect failed
update history for release v0.6.1
Merge pull request #160 from cloudwu/dev

release v0.6.1
only skynet.call response error
Merge remote-tracking branch 'cloudwu/master'