Update privacy policy for 2020 (#475)

*Update privacy policy for 2020*

Here is the older archived version:
#474

All changes should be live by Jan 1 for CCPA

Subprocessor list updated: https://segment.com/docs/legal/subprocessors/
Archived 2018- 2019 policy: https://segment.com/docs/legal/privacy-updates/
Link to 2019 in privacy-update doc: https://segment.com/docs/legal/privacy-2019/
Ship 2020: https://segment.com/docs/legal/privacy

Author: ladanazita