run_tests: use same everywhere and clean test dir on success
clean: moved tools into shinkenplugins package. adapted code for this change.

+ few clean change in test_check_x224
Updated shinkenplugins version.

and little clean.
clean TestPlugin.execute.

removed unnecessary assert.
Use assertRegexpMatches.
make sure to restore sys.stdout in all cases.
Use new shinkenplugins.
Change: converted test-ceilometer to nosetests.
1 missed NL on EOF.