Added an autoOrient utility in oae-util/image

Rather then adding autoOrient on all of the ImageUtil methods, I've added
an extra method that can be used for this. `autoOrient` simply brings
to much overhead and a performance degradation to execute it on each
image operation.

For example, doing an `autoOrient` once on the source preview image rather
then on each single one, results in a performance improvement of around
36 percent.

I've also added `autoOrient` to the profile pictures so that they can be
displayed correctly in the browser.
Better handling of bad input for remote preview images

We're now better handling flickr, slideshare and vimeo inputs.
If an image has no thumbnail, it will be ignored.
PR followup on auto orienting

ImageUtil.autoOrient now takes 2 optional arguments
 * removeInput === true:   This will unlink the input image.
 * outputPath 				Specify where the output should be written to.
All preview images are now jpgs as they are smaller and faster to generate.
Merge branch 'autoOrientImprovement' of git://github.com/simong/Hilary into autoOrientImprovement