Use shell to execute commands inside docker container as a buggy docker-py client exec_start api sometimes hangs.
Also fix the test container scapy and scapy-ssl_tls versions

Change-Id: I2cc3a22f8d4143253caaa2f26ab5c27afd365c41
diff --git a/src/test/utils/CordContainer.py b/src/test/utils/CordContainer.py
index 81addcb..95cc477 100644
--- a/src/test/utils/CordContainer.py
+++ b/src/test/utils/CordContainer.py
@@ -180,7 +180,7 @@
                     ip.link('set', index=guest, state='up')
                 index += 1
 
-    def execute(self, cmd, tty = True, stream = False, shell = False):
+    def execute(self, cmd, tty = True, stream = False, shell = True):
         res = 0
         if type(cmd) == str:
             cmds = (cmd,)