Require image_optim only during ImageOptimization#run_check

Change-Id: If508f37c272b9b8f8dd34def31bc7007d0ab6a93
Reviewed-on: https://gerrit.causes.com/30490
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Add jpeg as a filetype to image_optimization plugin

Change-Id: I01f4bf841f7316e494f157dd5d2617e1354d09d4
Reviewed-on: https://gerrit.causes.com/30491
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>