Add-on Configuration: 2 pts

[skleinfeldt]

As a content editor I will be able to use plone.app.imagecropping to crop Images and lead images, and I will be able to use Mosaic to create tiled layouts.

• Add imagecropping to python and install dependencies
• Add mosaic to python and install dependencies
• Add tesserae to python and install dependencies
• Add version pins for all of the above to custom buildout

[alecpm]

There are some issues with step ordering in the tesserae install profile that's preventing it from being installed, but there's a branch that implements this story/5-addons.