Fixed group filter parsing in boolean filters.

[axl8713]

Group filter was missing in the list of parsable filters in the AND and OR search filters.
This caused to have filters like the following ignored:

<OR>
    <FIELD>
        <field>NAME</field>
        <operator>ILIKE</operator>
        <value>%user%</value>
    </FIELD>
    <AND>
        <NOT>
            <CATEGORY>
                <operator>EQUAL_TO</operator>
                <name>MAP</name>
            </CATEGORY>
        </NOT>
        <NOT>
            <GROUP>
                <operator>ILIKE</operator>
                <names>%group%</names>
            </GROUP>
        </NOT>
    </AND>
</OR>