transport-xmpp: Fix ExcludedResourcesCallback

A copy&paste error…
Improve ContactUtil

return null if module-contactsread is not installed. This should have
been already the case, but it wasn't for a few methods.

To prevent:

E/MAXS/ModuleService(10978): java.lang.NullPointerException
E/MAXS/ModuleService(10978):    at org.projectmaxs.shared.module.ContactUtil.contactsByName(ContactUtil.java:311)
E/MAXS/ModuleService(10978):    at org.projectmaxs.shared.module.ContactUtil.lookupContacts(ContactUtil.java:126)
E/MAXS/ModuleService(10978):    at org.projectmaxs.module.smssend.commands.SmsSend.execute(SmsSend.java:55)
E/MAXS/ModuleService(10978):    at org.projectmaxs.shared.module.MAXSModuleIntentService.onHandleIntent(MAXSModuleIntentService.java:168)
E/MAXS/ModuleService(10978):    at org.projectmaxs.shared.module.MAXSModuleIntentService$ServiceHandler.handleMessage(MAXSModuleIntentService.java:71)
E/MAXS/ModuleService(10978):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/MAXS/ModuleService(10978):    at android.os.Looper.loop(Looper.java:176)
E/MAXS/ModuleService(10978):    at android.os.HandlerThread.run(HandlerThread.java:60)
transport-xmpp: Use Smack 4.1.0-alpha4 and jxmpp 0.4.0-alpha2

And make use of jxmpp-jid.

Remove ReconnectionManager from ProGuard keept classes, as we don't use it