fixes #8378 - check umask before installation

```
[root@katello-centos6-bats ~]# umask 027
[root@katello-centos6-bats ~]# katello-installer 
A umask no more restrictive than 0022 is required in order to install Katello.
```

We need to check each value for group, owner, and world to make sure it's no more restrictive than `0022`. 

I don't know if there's a fancier way to compare the umask - I imagine there's probably something one could do with some kind of bit-level math, but I couldn't figure one out.