run: Give more helpful message when user chooses an invalid test type

This is a solution for issue #175.

With the recent switch kvm-> qemu, it's natural that
people mistake those for a while. We haven't been handling
that case well. So let's establish valid test types and,
if the user chooses an invalid one, give him/her an
understandable error message.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
run: When creating an empty set, ask user to verify input

This is a solution for issue #176.

If you did type a test name that is not available for
the guest type you want the test to run, explain
carefully to the user that he/she needs to double
check the input, explaining some common mistakes.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
standalone_test: Show filters applied in config file

This is a solution for issue #178.

Display options values when displaying the list of
tests. That will explain the filters applied in the
config set generated by the config file.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>