- Remove mention of python 2.4 specific modules, as that version
  is not supported anymore
- Add bitarray and ipaddr
- Remove a double space
- Add mandatory C library packages too
- Mention the option of using drbd modules directly from your kernel

This also fixes Issue 372.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>