Added active element to Dirac
(refs #2370)
std::vector<bool> is not thread safe
(refs #2370)
Remove un-wanted parameter (refs #2370)
Merge pull request #3415 from aeslaughter/dirac-thread

Address threading issue for Dirac Kernels
Merge commit '70a1b86e396b3e7a33611931dca582c20593c3e7'