[SPARK-4920][UI] add version on master and worker page for standalone mode

Author: Zhang, Liye <liye.zhang@intel.com>

Closes #3769 from liyezhang556520/spark-4920_WebVersion and squashes the following commits:

3bb7e0d [Zhang, Liye] add version on master and worker page
[SPARK-4882] Register PythonBroadcast with Kryo so that PySpark works with KryoSerializer

This PR fixes an issue where PySpark broadcast variables caused NullPointerExceptions if KryoSerializer was used.  The fix is to register PythonBroadcast with Kryo so that it's deserialized with a KryoJavaSerializer.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #3831 from JoshRosen/SPARK-4882 and squashes the following commits:

0466c7a [Josh Rosen] Register PythonBroadcast with Kryo.
d5b409f [Josh Rosen] Enable registrationRequired, which would have caught this bug.
069d8a7 [Josh Rosen] Add failing test for SPARK-4882