cloudformation: open tcp/9418 for git

We need to use the git protocol to access read-only git repos.  It's a
quirk that when these are referenced from pip files, they need to go
over a source control protocol.  I wish it could go over http/s or ssh,
but it can't, so port 9418 it is.

I had to open inbound and outbound 9418 to get this working, don't know
why.  Leaving both open for now, will debug later so we can close down.

cloudformation_templates/edx-reference-architecture.json

@@ -1316,6 +1316,12 @@
             "CidrIp":{
               "Ref":"SSHLocation"
             }
+          },
+          {
+            "IpProtocol":"tcp",
+            "FromPort":"9418",
+            "ToPort":"9418",
+            "CidrIp":"0.0.0.0/0"
           }
         ],
         "SecurityGroupEgress":[
@@ -1338,6 +1344,12 @@
             "CidrIp":{
               "Ref":"SSHLocation"
             }
+          },
+          {
+            "IpProtocol":"tcp",
+            "FromPort":"9418",
+            "ToPort":"9418",
+            "CidrIp":"0.0.0.0/0"
           }
         ]
       }