Merge remote-tracking branch 'brson/nocommupstream'

Conflicts:
	src/libcore/private.rs
	src/libcore/task/mod.rs
	src/libcore/task/spawn.rs
	src/libstd/net_tcp.rs
	src/libstd/uv_global_loop.rs
	src/libstd/uv_iotask.rs