Avoid using Python for simple sleep

[ignatenkobrain]

shared_child.rs/src/lib.rs

Lines 240 to 244 in 8ca2d65

	pub fn sleep_forever_cmd() -> Command {
	let mut cmd = Command::new("python");
	cmd.arg("-c").arg("import time; time.sleep(1000000)");
	cmd
	}

Isn't sleep enough?

[oconnor663]

These tests need to work on Windows, so just using /usr/bin/sleep won't work. It probably would be cleaner to use included Rust binaries though. Whatever we decide to do with oconnor663/duct.rs#73 and oconnor663/os_pipe.rs#18, we should probably replicate here.