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.
Status Job ID Name Coverage
  Build Src
passed #3226
build:src

00:11

 
  Build Pkg
passed #3227
build:pkg

00:21

 
  Upload
passed #3228
upload:pkg

00:16