Adds new tag for testonly packages in package lists

Also introduces a new parameter INSTALL_TESTONLY_PACKAGES
in the stackrc with False as default value. Setting it to
True stack.sh will install all packages tagged with the tag
testonly in the package lists.

Includes needed packages for Ubuntu and Fedora

fixes bug #1203680

Change-Id: I911a6601819a34262853bba0658f6751148bfbec
Merge branch '38127-testonly' into dt-test