run: Introduce test job stats display v2

It is frequently useful to know how long a total
test sequence took to run, how many tests passed
and failed total, and the success rate, specially
in longer test jobs. Create a report function
that displays this info. As an example, here it's
how it looks:

./run -t qemu --tests migrate.with_reboot
SETUP: PASS (1.30 s)
DATA DIR: /home/lmr/virt_test
DEBUG LOG:
/home/lmr/Code/virt-test.git/logs/run-2013-02-18-16.46.48/debug.log
TESTS: 4
(1/4) migrate.with_reboot.tcp: PASS (51.62 s)
(2/4) migrate.with_reboot.unix: PASS (52.86 s)
(3/4) migrate.with_reboot.exec: FAIL (409.05 s)
(4/4) migrate.with_reboot.fd: PASS (59.65 s)
TOTAL TIME: 573.19 s (09:33)
TESTS PASSED: 3
TESTS FAILED: 1
SUCCESS RATE: 75.00 %

Make this reporting function print both to stdout and
to the debug log.

Changes from v1:

We have conventioned that TestNAError (SKIP) and
TestWarning (WARN) are not failures, considering that
in the first case, the case wasn't executed, and in
the second case, a condition happened, but it is not
alarming enough to consider the test as failed. Also,
it is important to mention that this job report is there
only as quick reference for the person running the
tests, not a substitute for analyzing test results.

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