rust-chg: depend on log and tokio_timer I'll start porting the daemon management functions from chg of C, which will be difficult to debug without some logging facility. AFAIK, the log crate is easy-to-use and widely used. tokio_timer provides sleep() helper to be used while spawning a server process.

rust-chg: suppress panic while writing chg error to stderr Otherwise "chg >/dev/full 2>&1" would exit with 101. Spotted by test-basic.t.