Make the roster easier to inspect.

The __repr__ version now looks like a regular dictionary.

sleekxmpp/roster/item.py

@@ -482,3 +482,6 @@ class RosterItem(object):
         a roster reset request.
         """
         self.resources = {}
+
+    def __repr__(self):
+        return repr(self._state)

sleekxmpp/roster/multi.py

@@ -182,3 +182,6 @@ class Roster(object):
         self._auto_subscribe = value
         for node in self._rosters:
             self._rosters[node].auto_subscribe = value
+
+    def __repr__(self):
+        return repr(self._rosters)

sleekxmpp/roster/single.py

@@ -285,3 +285,6 @@ class RosterNode(object):
             if not self.xmpp.sentpresence:
                 self.xmpp.event('sent_presence')
                 self.xmpp.sentpresence = True
+
+    def __repr__(self):
+        return repr(self._jids)