restore selinux label for dhcp network scripts

The `ifcfg-eth0` script does not have the correct selinux label.

This PR corrects the label after modifying network files in `miqnet.sh`
There may be another lingering issue with this file. But since cfme-setup.sh does the same restorecon, it should probably be covered.

Sample Error:
```
type=AVC msg=audit(1410252632.122:1117): avc:  denied  { getattr } for  pid=20072 comm="grep" path="/etc/sysconfig/network-scripts/ifcfg-eth0" dev=dm-0 ino=131095 scontext=system_u:system_r:dhcpc_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file
```

/cc @jrafanie @abellotti 
@kbrock Sorry, I mis-read the code.  Yes, the file is created with a ```.tmp``` extension.  My question is still: If we copy to a backup file then echo into the original file, do we still need the relabel?