* develop: (66 commits)
  Delete client.log0.0
  not start mqtt module by default, fot it not finished yet
  add one line back for double insurance
  [TD-364] broken link is not handled in right way
  Add mqtt plugin to subscribe to telemetry data
  remove extra case list print out.
  scripts
  remove some log
  add randome insert many records with NULL then commit.
  [TD-388] drop dnode in community version
  add precalculation interface
  [td-225] update the test script
  [td-225] fix bugs.
  fix general/insert/insert_drop.sim error
  add error log when have to call pthread_cancel
  change forcestop() to stop() to emulate ctrl-c
  fix TD-394
  add test case to test insert then import scenario.
  jenkins
  fix duplicate table bug
  ...