[INTERNAL] fix for commit 5ef77e7d11f5ca82c7b867edcfbc2ab7c269e9a1

String#split return an empty string if called on an empty string.

Since the XMPPConnectionService uses all entries in a list (which was
empty in this case) the Socks5Proxy had no candidates at all.

Change-Id: Ib01077f6df1a53bd618104c12cf7c926619ad332
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1413
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>