Feature: Use page title as default description

Feature/referer field

fix #111 auto file delete/original size preview

Also add css to restrict original-image size

For django-images, the AUTO-DELETE mark is required to remove files
automatically.

Fix tags being serialized as stringified map objects

This commit fixes an issue where the `tags` key of pins in the API response would be serialized as the string `"<map object at 0x...>". This issue would cause a `TypeError: pins.objects[i].tags.sort is not a function` on the frontend and prevent the page from loading.

Fix Timestrap => Pinry typo

Add Travis CI test

Fix miss tag

Remove the need for jQuery in bookmarklet.

Remove explicit http image for gravatar images