audit: Add startup script

The startup script for the audit package did not meet the buildroot
standards when the package was initially merged. Adding a compliant
startup script for starting the audit daemon along with rotating the
logs and other features.

[Thomas:
  - Replace "Failed" by "FAIL" to be consistent with the rest of the
    init script and other packages
  - Use $(INSTALL) -D with a complete destination path to avoid having
    to create /etc/init.d before installing the init script.]

Signed-off-by: Clayton Shotwell <clayton.shotwell@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>