init: Add support for some cmdline args

This patch adds support for setting keyboard layout/use_strong_rng/
disable_aes_ni/nfsv4_domain in cmdline args:
keyboard=layout(eg:keyboard=us)
use_strong_rng=<bytes>
disable_aes_ni=[y|n]
nfsv4_domain=domain
This informations are used to set keyboard layout/use_strong_rng/
disable_aes_ni/nfsv4_domain during an auto-installation.

Change-Id: I9f0f972c4b2cef433269567f25646869d010d30b
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=960846
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=911835
Signed-off-by: hadong <hadong0720@gmail.com>