Non-HTTP[S] links trigger the linked file feature.

[bharathcs]

As far as I can tell, mailto links in canvas pages are treated as linked files, CanvasSync tries to download with that link and fails.

Here's an example of the canvas page html: <p><a href="mailto:*****@***.**">*****@***.**</a></p>

This is a pretty low impact bug in the mailto:... case (only results in a long list of failed file downloads). Might be a little bit worse if a file:// link is used (Didn't test, I'm not sure how the library would deal with a real local file present somewhere).

Fix should just be checking the URL scheme, and only going for the HTTP / HTTPS links.