Bug 439017 - use timeout while waiting on condition

Introduced TestUtil.waitWhile() and AbstractDebugTest.waitWhile()
methods to allow tests to fail if some condition does not change after a
given timeout. This should give some hints about test failures without
crashing (DNF) entire test suite.

Also introduced AbstractViewerModelTest to remove lot of copy/paste code
from related tests.

Change-Id: I435872c74482f86e87a42f286834200ef3b45bfe
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
24 files changed