Use blobstore for images

Previously images and icons were stored in the datastore as properties
on the recipe. Now images are stored in the blobstore and referenced to
in the Recipe model. The image server can handle resizing for icons,
etc..

Includes changes to the service to pass back a URL for the image in a
get recipe call
Generate blobstore upload URLs on-demand

Make a call to get an upload url when the file is dragged onto the
control rather than in the FoodieHandler.
Cleaned up some old "temp" file stuff

Removed unused TempFile mode class and removed "temp" from the url
Merge pull request #24 from teajay/ImgCloudShit

Move image storage to blobstore