Importing bin/sh

/etc/profile enables by default tabcompletion, as well as emacs mode,
in order to keep the old MINIX ash behavior.

Note: The shell now refuses to source a script without a relative or
      absolute path.
      This means:
        - '. myscript.sh' fails, while
        - '. ./myscript.sh' succeeds

Change-Id: I0be89b0747bd005e4c05cadb937af86883627dc6