Add basic support for web fonts. Synchronous loading only
for now, and only deals with TTF format fonts.

For an example, try loading http://icons.marekventur.de
Fix missing license header in new file.
Address review comments.
Don't rely on font hint for format detection. Handle parsing comma
separated format hints. Fix oversight in mac code dealing with
creating web fonts from memory.
Update font face to new url parser.
Fix parsing invalid url, clean up font template matching.
Fail if the snapshot cannot be fetched
Rename RenderMsg to RenderInitMsg

RenderMsg doesn't actually render anything, so the name is confusing.
Rename ReRenderMsg to RenderMsg

ReRenderMsg is also used for rendering the first time, so the name is
confusing.
Merge pull request #3026 from Manishearth/fail-on-wget

Fail if the snapshot cannot be fetched
Merge pull request #3027 from zwarich/render-msg-renames

Rename messages used in rendering
Merge pull request #2791 from glennw/web-fonts

Add basic support for web fonts. Synchronous loading only
activate wpt-tests on linux travis file