Upgrade pillow to 5.3.0

[fabaff]

Description:

Changelog: https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst#530-2018-10-01

Example entry for configuration.yaml (if applicable):

camera:
  - platform: generic
    name: Bärenplatz
    still_image_url: http://www.baerenplatz.be/assets/images/live.jpg
  - platform: proxy
    entity_id: camera.barenplatz
    max_stream_width: 360
    max_image_width: 720

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable ([example][ex-requir]).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.