Ensure that 'check' and 'sign' do the same thing

Specifically they should both add the subject CN to the set of
subjectAltNames. Also add a small test script to verify that signing
works using the command-line tool.
3 jobs for master in 48 seconds
Status Name Job ID Coverage
  Build Src
passed build:src #3226

00:00:11

 
  Build Pkg
passed build:pkg #3227

00:00:21

 
  Upload
passed upload:pkg #3228

00:00:16