Plugin: user service - add new request type: grouplist & usergrouplist which returns xml with groupnames elements containing all group names or group names of a user.
Fix 'RFC 6121 8.5.1.  No Such User' for IQ stanzas

IQ stanzas, which were routed to a non-existent user were falsely replied to with an IQ-result (e.g. ping).
This fix checks for the existence of the user and returns an error, in case the user does not exist.
OF-397 Do not deliver offline messages to clients with negative priority

As per RFC 6121 8.5.2.1.1. Message and XEP-0160
OF-818 Message routing to bare JID can route to negative priority resources

This commit fixes the regression, that was introduced with the addition of Message Carbons.
Message Carbons are delivered to all non-negative sessions.
If there's no Message Carbons-enabled session, it will be delivered to the highest priority session only.
OF-805 [MUC] OF does not return all affiliated users when requesting multiple affiliations

When requesting:
<iq type="get" to="6ace0fd2f59f13c2484336dd06b4462a@bizmanager.msz006" id="getRoomMemberList">
<query xmlns="http://jabber.org/protocol/muc#admin">
<item affiliation="member"/>
<item affiliation="owner"/>
<item affiliation="admin"/>
</query>
</iq>

Openfire does only return admins (the last requested affiliation).
This fix rectifies this.
Remove dispensable logic in the IQOwnerHandler, which deals with MUC affiliation changes

MUC affiliations are managed in the #admin namespace, not in the #owner namespace.
This is already a minor contribution to OF-178 (Updating MUC to latest version).
Merge pull request #42 from sco0ter/of178

Remove dispensable logic in the IQOwnerHandler, which deals with MUC aff...
Merge pull request #41 from sco0ter/of805

OF-805 [MUC] OF does not return all affiliated users when requesting mul...
Merge pull request #38 from sco0ter/of810

Fix 'RFC 6121 8.5.1. No Such User' for IQ stanzas
Merge pull request #40 from sco0ter/of818

OF-818 Message routing to bare JID can route to negative priority resour...
Merge pull request #39 from sco0ter/of397

OF-397 Do not deliver offline messages to clients with negative priority
Merge pull request #21 from meneo/master

Plugin: user service - add new request type: grouplist & usergrouplist