Write up a 2i2c Hub Engineer guide to user data privacy

[choldgraf]

Background

It will be really important that 2i2c is trusted to respect user data privacy. We will likely have access to everything on a given Hub, which means that we may have access to potentially sensitive user data (like usernames etc). We need to make sure that we adhere to best-practices in data privacy do that we retain the trust of our customers.

To Do

We should create something like the "ten commandments for hub engineers and user data". Things that every engineer must keep in mind any time we work on a specific hub with potentially sensitive information (e.g., things like "don't copy username data outside the hub". This should be a public document that we use to show the world that we take this seriously.

@yuvipanda I wonder if you know of any best-practices or documents like this from your time at Wikimedia?

[choldgraf]

closing in favor of #302