Add Google Play Services attribution info

[barbeau]

Summary:

We need to add attribution for Google Maps API v2:

If you use the Google Maps Android API in your application, you must include the Google Play Services attribution text as part of a "Legal Notices" section in your application. Including legal notices as an independent menu item, or as part of an "About" menu item, is recommended.

The attribution text is available by making a call to GooglePlayServicesUtil.getOpenSourceSoftwareLicenseInfo

http://developer.android.com/reference/com/google/android/gms/common/GooglePlayServicesUtil.html#getOpenSourceSoftwareLicenseInfo(android.content.Context)

There is an open maps-api issue about the amount of text that getOpenSourceSoftwareLicenseInfo() returns here:
https://code.google.com/p/gmaps-api-issues/issues/detail?id=8660

Simply setting it to a TextView causes Help to load with a large latency. I need to look into how to potentially fix this - see https://code.google.com/p/gmaps-api-issues/issues/detail?id=8660#c8.

See also OneBusAway/onebusaway-android#600.

[barbeau]

Per https://developers.google.com/android/reference/com/google/android/gms/common/GoogleApiAvailability#getOpenSourceSoftwareLicenseInfo(android.content.Context), this is no longer required.