Speed up deploy process

"bundle install" was running on the deploy steps where it wasn't needed.

Moved the "bundle install" into the build step and sourced the deploy
steps from the tiny "alpine" base image.
2 jobs for deploy-faster in 46 seconds
Status Job ID Name Coverage
  Build
passed #6392
build

00:00:33

 
  Deploy
passed #6393
deploy_staging

00:00:12