Added more status images to README.rst
Added more status images to README.rst

Details:
- Add 'Latest pypi version' status image.
- Add 'Download per Month' status image.

Signed-off-by: Juergen Leopold <2ef4e6fc356c4a0c570adb4e83b64b658f380892@de.ibm.com>

zhmcclient/python-zhmcclient,zhmcclient/python-zhmcclient