CSIT-1139: Implement parallel test execution

The implementation of parallel test execution in VPP Test Framework.
- VPPTestCase test methods are grouped together
- tests are running in separate processes
- VPP instances spawned by tests are assigned to different cores
- output from these processes is redirected through pipes and printed
out testcase by testcase
- TEST_JOBS env var is used to specify the number of parallel processes
- improved test summary
- a bit of code cleanup

Change-Id: I9ca93904d9fe2c3daf980500c64a8611838ae28c
Signed-off-by: juraj.linkes <juraj.linkes@pantheon.tech>

test/log.py

@@ -38,8 +38,9 @@ else:
     log_level = 40
 
 handler = logging.StreamHandler(sys.stdout)
-handler.setFormatter(ColorFormatter(fmt='%(asctime)s,%(msecs)03d %(message)s',
-                                    datefmt="%H:%M:%S"))
+color_formatter = ColorFormatter(fmt='%(asctime)s,%(msecs)03d %(message)s',
+                                 datefmt="%H:%M:%S")
+handler.setFormatter(color_formatter)
 handler.setLevel(log_level)
 
 global_logger = logging.getLogger()
@@ -54,6 +55,16 @@ def getLogger(name):
     logger.setLevel(logging.DEBUG)
     return logger
 
+
+def get_parallel_logger(stream):
+    logger = logging.getLogger('parallel_logger_{}'.format(stream))
+    logger.propagate = False
+    handler = logging.StreamHandler(stream)
+    handler.setFormatter(color_formatter)
+    handler.setLevel(log_level)
+    logger.addHandler(handler)
+    return logger
+
 # Static variables to store color formatting strings.
 #
 # These variables (RED, GREEN, YELLOW and LPURPLE) are used to configure