Add support for images in Views integration

Quoting OP from http://drupal.org/node/1244166:

WRT to the view image field, I think people are used to the flexibility that imagefield & imagecache provide when used with views, so I'd aim to provide a similar flexibility. Since the ContentDM backend seems easily able to deliver any image derivative (scale/width/height) I'd aim to make it as flexible as possible, letting people define their own presets and deciding what's a thumbnail and what's a larger image, just as we do with views/imagefield/imagecache. I see the ContentDM API has separate getthumbnail and getimage calls, and I'm not sure what the difference is – any reason to stick with thumbnails?

Yes, there is a reason to stick with thumbnails: every item in a CONTENTdm collection has one, regardless of whether the item is an image, a compound item (like a book), a video, or whatever. If you don't supply a thumbail when you create the item, CONTENTdm supplies a defult one. I think that if we expand what we can put in to a View, we should include both the default CONTENTdm thumbnail and support for more flexible file-processing utilities.

Also, don't forget that the CONTENTdm Integration module doesn't store _any_ thumbnails or media files of any sort on the local Drupal. It only stores metadata and full text in the nodes. If we build in support for imagecache, etc., would we need to change that? I am reluctant to do that as part of the core CONTENTdm Integration module, but am open to allowing add-on modules to handle it.

Finally, I want to clarify that not every field in a CONTENTdm item is currently accessible to Views. On node creation, the module inspects the Dublin Core mapping of every field and creates node fields for every metadata element in the incoming item that has a DC mapping in the CONTENTdm collection configuration. Details on the DC-mapped fields that are created are available in contentdm.views.inc, they are the ones beginning 'dc_'.

I'd be happy to see everything about a CONTENTdm node integrated into Views, but I thought I'd clarify some of the architecture points of the CONTENTdm Integration module as it currenlty stands.

Pushed to commit d7369

Been testing this quite a bit and it appears to work as designed.