Added code for telling grub to ignore a kernel update

Previously, there was a problem with kernel updates:

If the RAM Session was updated but the Original OS was NOT (through
'sudo rupdate'), the Original OS would fail to boot because it didn't
have the /lib/modules necessary to work with the new kernel.

This commit makes rupdate set an ENV variable (IGNORE_KERNEL) in cases
where the RAM Session received a kernel update but the Original OS
did not. Grub can read this variable, and not create entries for new
kernels that the Original OS can't boot anyway.

Note: This will NOT work yet, as I also need a sed line that changes
/etc/grub.d/10_linux to actually care about the message
Added sed line to change /etc/grub.d/10_linux
Prevent grub from generating entries when no kernel modules available
Added code to Uninstall function to revert /etc/grub.d/10_linux
Merge branch 'master' into kernel_update_permanent_fix
Merge branch 'kernel_update_permanent_fix'