show better warning when running image_optim for a directory without recursive option
use stable sort for workers and explicitly sort by run_order
remove comparison of workers (by run_order)
Merge branch 'stable-sort-workers'
add GlobHelpers.expand_braces as ruby before 2.0 doesn’t support expanding curly braces in globs
add exclusion glob patterns; closes #35, resolves #48
add example of using recursive option to readme
Merge branch 'exclude-files'