Only show Google Maps prompt once

[barbeau]

Summary:

Some users don't want to install Google Play Services just to use the app. Right now, every time the app is launched we prompt them to do this, with options for "No Thanks" or "Install". We should only prompt once for this, and remember the user's preference instead of asking the user on every app start.

Steps to reproduce:

1. Start the app on a device without Google Play Services installed
2. Tap "No, thanks" when prompted to install Google Maps
3. Exit and restart the app

Expected behavior:

Remember my preference not to install Google Maps

Observed behavior:

App prompts again if you'd like to install Google Maps, even if you've already said no.

Device and Android version:

N/A