[INTERNAL] applied changes for SMACK API change

The SMACK API no longer adds the cause exception to the XMPPException
during XMPPConnection.connect() so we now have to rely on the error
code of the XMPP error only.


Change-Id: I511f3052313d26b6b38d79e0d3ea8b4d0f651f43
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1222
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>