Implement orx:max-pixels attribute to scale down images about collect HOT 9 CLOSED

With http://groupcomplete.com, we resize captured images so that they fit within 1024x768.
 This was a necessity for us since shipping around 2-3Mb+ images is impractical.  We
also downgraded the image quality somewhat but not enough to impact overall image integrity.

Attached is a patch against 2a190d8613ca that does just this.  It works on 2.2+ (might
work on 2.1 but I have not verified).  The only caveat is that phones with a smaller
app heap might run out of memory resizing larger photos.

Turning this into a preference is left as an exercise for the reader.

For maximum flexibility, I would suggest implementing this as a set of form image attributes
that would "request" maximum image dimensions as well as quality level.

If the device image capture preferences are set to "auto" the form hints would be used.
 Otherwise, the device image capture preferences would override and supply an image
of a different dimension and quality.

The form hints could be displayed on the image capture screen with easy access to adjust
the image capture settings on a per-image basis or perhaps simply redirect to the device
image capture preferences.

Actually, this is useful enough that we might end up implementing it ourselves.

The Android devices I checked all have some way to resize the picture size inside the
Camera app itself, so I think that's the best way to go.