Don't build package by default.
Small bugfixes in sub.mk.
Update to latest Rust.
Renderer might have exited before compositor knows its gone.

This works around the problem, which will need a more detailed fix when it
gets revamped.
Run one contenttest at a time.
Disable contenttest on linux because it doesn't work anyway.
auto merge of #1067 : metajack/servo/rust-up-20131014, r=jdm

This upgrades to this morning's master. We have unfortunately broken the Android build, but I will update that in a second pull request as I think it's more than a single upgrade behind.