[COOK-759] Added LWRPs for configuring SELinux 

3 LWRPs for working with SELinux

`selinux_bool` - switch booleans on and off
`selinux_policy` - builds and installs local policy from .te file
`selinux_restorecon` - restores file contexts to single files or directories

See README.md for usage examples. Please note I've only tested these on CentOS6. CLA is submitted and awaiting approval.