This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Treating TIFF and BMP as images cause us to add them to IMG tags, this is very inconsistent across browsers.
You can still upload these files they will simply not be displayed in IMG tags.
Sam Saffron
Penar Musaraj
Guo Xiang Tan
Neil Lalonde