Fix uninitialized variable in DateValidator

Picked up by coverity.
Refs #9946
Add unit test for Matrix transpose.

Coverity detected an issue that looks like a false-positive but there was
no unit test for it. Valgrind says there isn't and it looks like it is
just an artifact of how the code/memory is Matrix is structured.
Refs #9946
Fix coverity warning about thread-safe access in DataService

Refs #9946
Style clean up in Kernel::DataService.

* remove any mention of workspace
* use camelCase naming rather than underscore naming
Refs #9946
Merge branch 'bugfix/9946_coverity_issues_kernel' into develop