Adding support to include custom tests while triggering Jenkins Jobs.

Changes in components like backup, exporter, logging with no change in test framework necessitate quick run of component tests respectively with the new image.

This at the moment can be achieved by specifying tests in Custom suite which in turn is generated through a gerrit review.

Hence, It would be nice to have a field in our list of Jenkins params to specify the custom tests which we want to run while triggering the job rather than the cumbersome process to generate a custom suite to do so.

Dev Env. has the functionality to specify the tests during run time, we need to replicate the same in QE setup.

CC: Roo Thorp