[RELEASED] Image upload

Imgur integration is pretty simple. Currently, I'm using the public API which gives about 1,250 image uploads per day. There are a couple of bugs I'd fix in the JS in the existing code. The endpoint for the free endpoint is occasionally temperamental.

They have a zero cost (basic plan) API which allows 100,000 uploads per month. It's a little more work to implement this and I don't imagine we're close to hitting 1,250 image uploads, so I haven't bothered with it.

The free version has this caveat:
The Imgur API is free for non-commercial usage. Your application is probably free if you don't plan on making any money with it, or if it's open source.

It's open source and it is free to use, with a donation button, which I don't think counts. Yah, I was planning on adding this with the v2, but we can have it setup for the v1. I can setup an account so that we can track and manage it better.

Turn the image button into a dropdown. Clicking the button or By URL... does what it does now. Upload to Imgur is a file upload and it then inserts the code into the editor.



The code's ready to check-in. If you want to generate/change the Imgur public API key then it's in the JS (although the one in there is just for GP).