Unittest - Add mechanism to skip task and taskd tests

* When testing multiple clients vs server versions, repeating client
tests is unnecessary. By setting the env variables TASKW_SKIP and
TASKD_SKIP it will now be possible to skip all task (client only) and
taskd (client + server) tests, respectively.

test/basetest/utils.py

@@ -13,6 +13,10 @@ from .exceptions import CommandError
 USED_PORTS = set()
 ON_POSIX = 'posix' in sys.builtin_module_names
 
+# Environment flags to control skipping of task and taskd tests
+TASKW_SKIP = os.environ.get("TASKW_SKIP", False)
+TASKD_SKIP = os.environ.get("TASKD_SKIP", False)
+
 
 def wait_process(proc, timeout=1):
     """Wait for process to finish