Remove explicit http image for gravatar images

bookmarklet improvements to the image preview

Improve description text rendering

Update to Django 1.8 and tastypie 0.12

Closes #38, closes #88

Fix N+1 queries in pin loading

Case insensitive sorting of tags in javascript

The optimization broke image uploading, this fixes it again.

This saves another three queries per pin, bringing to total query count
down to 8.

See issue #85 .

Fetch the submitter with a join and get all the images and tags in one
query each. This reduces the total query count for loading 50 pins from
304 to 158.

See issue #85.

[bookmarklet] allow closing with ESC or clicking on header.

- show the image size on top of the preview.
- scale down the preview to view (most) of the image instead of just the center.

On close, remove the script as well as the images.

Remove race condition waiting for proper event instead of fixed time