Merge in CASA/casa6 from CAS-14357 to master
* commit '1c1ed89c02d57f7772e27937a1e21b723f01ca7c':
Add check for when component list is empty. If yes, use default list of tests
Add update to documentation for rcdir, fix for bug in converter when test crash with segfault using xmlrunner
Rename rcdir to new parameter cachedir. path to users writable folder for internal files (formerly this was set using rcdir)