Adding support for shifting RGB Colors.

Based on: http://www.pixastic.com/lib/docs/actions/coloradjust/
Merge branch 'feature/rgb-shift-imagae-transformer' of github.com:bstopp/acs-aem-commons into bstopp-feature/rgb-shift-imagae-transformer
Merge branch 'master' into bstopp-feature/rgb-shift-imagae-transformer