Listen for insertion of data fitting the configured workouts

[strooooke]

... and automatically mark them as done, canceling the reminder for them.

Problem: using https://developers.google.com/android/reference/com/google/android/gms/fitness/SessionsApi.html#registerForSessions(com.google.android.gms.common.api.GoogleApiClient,%20android.app.PendingIntent) allows only listening for sessions that got explicitely started, not for sessions inserted after the fact (like quickfit itself does it). Also, stuff like walking around as collected by the Google Fit app itself from sensor data does not get consolidated into a session.