* dev: (49 commits)
  upgraded the version of core,  explorer and test module to 1.5.0-SNAPSHOT;
  published 1.4.0.RELEASE;
  upgraded modules;
  update log configurations
  update contract samples
  update log configurations
  upgraded modules;
  upgraded modules to fix bugs of kvdb storage;
  add error rolling
  update gateway log configuration
  update log configurations
  fix jira 628, update bftsmart lib
  fix dataAccount sample error
  update bftsmart
  upgraded modules to fix the dead lock bugs of consensus thread that the consensus lock is held by a waiting thread;
  upgraded modules to fix the bugs of concurrent competition between the process of consensus and the process of Heartbeat;
  update samples
  upgraded modules;
  optimized the consensus testcases;
  upgraded modules;
  ...