Bug 1042255 - reuse timer for execute_parallel_action calls

* Ensure execute_parallel_action uses the same hourglass object for
  all operations
* Refactor using PathUtils.flock to remove redudant code
* Remove unused code
* Replace all calls to File.join with PathUtils.join. security issue.
* Optimize obtaining list of gears
* use node.conf rather than hardcoding values
Merge pull request #4391 from jwhonce/bug/1042255

Merged by openshift-bot