Added additional command line batch options

--hostname=<new_host_name>
--memory-split=<16|32|64|126|256>
--enable-camera|
--disable-camera
--overclock=<None|Modest|Medium|High|Turbo>

NB Some testing done. Further test cases welcome

Following message is displayed. Not sure if benin

$ sudo bash ./raspi-config --overclock=High
update-rc.d: using dependency based boot sequencing
update-rc.d: warning: default start runlevel arguments (2 3 4 5) do not match switch_cpu_governor Default-Start values (S)
update-rc.d: warning: default stop runlevel arguments (0 1 6) do not match switch_cpu_governor Default-Stop values (none)
Set overclock to preset High