fixed npe when user was very quick with starting to type in startConversationactivity

src/eu/siacs/conversations/ui/StartConversationActivity.java

@@ -482,9 +482,11 @@ public class StartConversationActivity extends XmppActivity {
 	}
 
 	protected void filter(String needle) {
+		if (xmppConnectionServiceBound) {
 			this.filterContacts(needle);
 			this.filterConferences(needle);
 		}
+	}
 
 	protected void filterContacts(String needle) {
 		this.contacts.clear();