Remove the direct azure dependencies from gfx, layout and layout_thread.

This does not cover transitive dependencies through canvas_traits, though that
should not be too hard to solve either.

components/layout_thread/Cargo.toml

@@ -11,7 +11,6 @@ path = "lib.rs"
 
 [dependencies]
 app_units = "0.3"
-azure = {git = "https://github.com/servo/rust-azure", features = ["plugins"]}
 euclid = "0.10.1"
 fnv = "1.0"
 gfx = {path = "../gfx"}