Clarify data collected and use better privacy policy

[jamespfluger]

Currently, the privacy policy does not properly specify what data is collected nor how it is used.

This task should rewrite the privacy policy and summarize it within the app. Maybe get something from an actual lawyer too?

The data directly collected in the app is all anonymous with no PII. It can be summarized as:

• Anonymous device ID, used to identify which device is what
• Anonymous Firebase token, used to send notifications via FCM
• Anonymous Amazon user ID, used to identify users logged in via Amazon
• Anonymous Alexa user ID, used to identify users through Alexa
• User-chosen name for their device

Also (somewhat) worth noting the information is encrypted at-rest and all web traffic is done through HTTPS

The data indirectly collected in the app is done through LWA and Crashlytics. We should link any privacy policies for these services, along with the clear ability to opt out of Crashlytics on #107

[jamespfluger]

Partially addressed by #112