onPacket and getChat expect to receive a bare JID.

This caused an exception when xabber observed another presence send a message to a contact and that contact respond thereafter:
> E/AndroidRuntime(19534): FATAL EXCEPTION: main
> E/AndroidRuntime(19534): java.lang.IllegalStateException
> E/AndroidRuntime(19534):        at com.xabber.android.data.message.MessageManager.addChat(MessageManager.java:166)
> E/AndroidRuntime(19534):        at com.xabber.android.data.message.MessageManager.createChat(MessageManager.java:155)
> E/AndroidRuntime(19534):        at com.xabber.android.data.message.MessageManager.displayForwardedMessage(MessageManager.java:516)
> E/AndroidRuntime(19534):        at com.xabber.xmpp.carbon.CarbonManager.onPacket(CarbonManager.java:229)
> E/AndroidRuntime(19534):        at com.xabber.android.data.connection.ConnectionManager.processPacket(ConnectionManager.java:275)
> E/AndroidRuntime(19534):        at com.xabber.android.data.connection.ConnectionThread$18.run(ConnectionThread.java:596)
> E/AndroidRuntime(19534):        at android.os.Handler.handleCallback(Handler.java:615)
> E/AndroidRuntime(19534):        at android.os.Handler.dispatchMessage(Handler.java:92)
> E/AndroidRuntime(19534):        at android.os.Looper.loop(Looper.java:137)
> E/AndroidRuntime(19534):        at android.app.ActivityThread.main(ActivityThread.java:4745)
> E/AndroidRuntime(19534):        at java.lang.reflect.Method.invokeNative(NativeMethod)
> E/AndroidRuntime(19534):        at java.lang.reflect.Method.invoke(Method.java:511)
> E/AndroidRuntime(19534):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
> E/AndroidRuntime(19534):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
> E/AndroidRuntime(19534):        at dalvik.system.NativeStart.main(Native Method)