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: fix missing comma in 'DATABASE' output

Happened to notice this while I was in here, mostly a cosmetic fix.
Merge pull request #37 from edx/feature/sef/refarch-gitproto

cloudformation: open tcp/9418 for git