Adding process signull

Hi,
I ran into an issue with the module today.  I noticed Nagios was reporting UNKNOWN for check_yum on the server I built and installed the RPM on yesterday.  
```
YUM_Updates;UNKNOWN;HARD;4;UNKNOWN: Security plugin for YUM is required. Try to 'yum install yum-security' and then re-run this plugin. Alternatively, to just alert on any update which does not require the security plugin, try --all-updates
```
I'm not exactly sure what caused it, but I was taking a look at the sebool options and may have enabled the network access around that time.  Anyway, I ran audit2allow against my logs and found a couple of changes to the TE file to be made.

Patched the TE file and updated the versions/release, built the package and was able to do an upgrade on the existing package just fine.

We're running on a mix of OracleLinux and CentOS, both version 6.x, mostly up to date.  Test box is showing:
```
YUM_Updates;OK;HARD;4;YUM OK: 0 Security Updates Available
```