Additional SELinux scripts

Created wrapper scripts around semanage fcontext and
restorecon commands.

For a lay person, these scripts are easier to understand. We also
check if SELinux is available within the script, so it will reduce
the amount of code currently in the SELinux orc scripts when they
are refactored.

Change-Id: I7fdd7d52e255a50d4900f35aba4b3390c68e6651
Merge "Additional SELinux scripts"