[SPARK-5315][Streaming] Fix reduceByWindow Java API not work bug

`reduceByWindow` for Java API is actually not Java compatible, change to make it Java compatible.

Current solution is to deprecate the old one and add a new API, but since old API actually is not correct, so is keeping the old one meaningful? just to keep the binary compatible? Also even adding new API still need to add to Mima exclusion, I'm not sure to change the API, or deprecate the old API and add a new one, which is the best solution?

Author: jerryshao <saisai.shao@intel.com>

Closes #4104 from jerryshao/SPARK-5315 and squashes the following commits:

5bc8987 [jerryshao] Address the comment
c7aa1b4 [jerryshao] Deprecate the old one to keep binary compatible
8e9dc67 [jerryshao] Fix JavaDStream reduceByWindow signature error