In order to keep things simple and clear, enforce the
following test results rules:

 * `PASS`: the test passed, which means all conditions
   being tested have passed.
 * `FAIL`: the test failed, which means at least one
   condition being tested has failed. Ideally, it should
   mean a problem in the software being tested has been found.
 * `ERROR`: an error happened during the test execution.
   This can happen, for example, if there's a bug in the test
   runner, in its libraries or if a resource breaks unexpectedly.
   Uncaught exceptions in the test code will also result in this
   status.
 * `SKIP`: the test runner decided a requested test should not
   be executed. This can happen, for example, due to missing
   requirements in the test environment or when there's a job
   timeout.

In order to do that, let's not make the behavior on exceptions
other than TestFail to be configurable. Therefore, the config
value uncaught_exception_result must be removed and the status
of the test always be 'ERROR'.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>