Update test cert generation script for postgresql

[ashfall]

This can be used to regenerate testing certs for postgres db connections.

Depends on #1160

[ashfall]

This addresses @cyli's comment from #1160 (comment)

[ecordell]

I've used something like this before:

command -v cfssljson  >/dev/null 2>&1 || { 
    echo >&2 "Installing cfssl tools"; go get -u github.com/cloudflare/cfssl/cmd/...;
}

[ashfall]

Thank you kindly. Will update! :)

[cyli]

Thanks for working on this! LGTM with the caveat that we might want to create the dir database first with mkdir -p in the script, just create it and check it into git, or alternately first merge #1160 before merging this PR.

[ashfall]

@cyli Thanks! I am going with getting #1160 merged first, unless there's a strong preference for the former?

[cyli]

Nope that works for me!

[riyazdf]

jenkins, test this please

[riyazdf]

code LGTM pending green on jenkins tests, and also we should open an issue to migrate the other cert generation bits in regnerateTestingCerts.sh to also use cfssl - it's a little odd to only use cfssl for certain certs and openssl for others

[ashfall]

@riyazdf Thanks! Filed #1168

[cyli]

There were no previous changes to that file, and seem to be no conflicts, so merging anyway :) Thanks @ashfall!