Move every test to a method on DenoTestCase.
test.py is a single TestSuite of every TestCase.
Add a Spawn context manager for http_server,
this is explicitly used where it's needed.
Each python test file can now be run independently
without needing to manually run http_server.
Add --help and consistent flags using argparse for
each python test, including --failfast.
Use ColorTextTestRunner so that '... ok' is green.
(Use C:\deno instead of c:\deno in appveyor config because it's cloned to c:\ by clone_folder variable in .appveyor.yml. On the other hand, build directory is pointed to C:\ by $(APPVEYOR_BUILD_FOLDER) so that test targets are placed on separated partitions.)
