Summary:
Previously, Remarkup allowed you to paste in an image URI and get an inline
image. However, it did this by hotlinking the image which isn't so hot in an
open source product.
Restore this feature, but use image proxying instead. The existing image macro
code does most of the work.
There is a mild security risk depending on the network setup so I've left this
default-disabled and made a note about it. It should be safe to enable for
Facebook.
Test Plan:
Pasted in image and non-image links, got reasonable behavior. Verified proxying
appears to work. Verified that file:// shenanigans produce 400.
Reviewed By: tuomaspelkonen
Reviewers: aran, jungejason, tuomaspelkonen
Commenters: cpiro
CC: aran, cpiro, tuomaspelkonen
Differential Revision: 214
