resolve pylint errors on Fedora 19

addressing:
```
    + pylint --rcfile=/etc/spacewalk-pylint.rc --additional-builtins=_ katello
    ************* Module katello.client.core.utils
    W1401:296,0: Anomalous backslash in string: '\0'. String constant might be missing an r prefix.
    W1401:298,0: Anomalous backslash in string: '\0'. String constant might be missing an r prefix.
    W1401:309,0: Anomalous backslash in string: '\0'. String constant might be missing an r prefix.
    W1401:320,0: Anomalous backslash in string: '\|'. String constant might be missing an r prefix.
```