Fixed most issues caused by libc being moved from std to it's own crate.

I just did a quick pass and fixed a majority of the simple issues but
there are still some problems with the following utils:
  id
  md5sum
  tee
  uptime
  users
  whoami
Accidentally removed an exclamation for crate_id in echo. Put it back.
Merge pull request #158 from PeteJodo/master

Fixed most issues caused by libc being moved from std to it's own crate.