tests: Improve test case base class
tests: Improve test case base class

Add a number of new methods and improve the start/stop of server.

The --noreload is particularly useful to avoid fork of manage.py and
make stop_server() work.

Signed-off-by: Fam Zheng <df9fd617995bad07eac70e27aa3fe5069270e3bd@redhat.com>

patchew-project/patchew,famz/patchew,famz/patchew,famz/patchew,famz/patchew,patchew-project/patchew,patchew-project/patchew,patchew-project/patchew