Add a way to trigger immediate backups

Send SIGUSR1 to the agent binary.
3 jobs for master in 1 minute and 55 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build Src
passed #9031
build:src

00:00:20

 
  Build Pkg
passed #9032
build:pkg

00:01:08

 
  Upload
passed #9033
upload:pkg

00:00:26