Add useful data to the notification when activity is running.

This PR adds gps status to a notification which will start when the StartActivity starts. It will disappear when the gps is stopping or when an activity is started. When an activity is started a notification will show distance, time and pace. (this will only show up on the phone) In Android L you will see this notification on your lock screen.

It would be nice to be able to start, pause, resume and stop from the notification but this isn't possible at the moment as all logic is in the activity and not the service.

The thought here is that this will prepare for some more features in a wear app. We can create a Wear-service in RunnerUp which communicates with the wear app. When pressing an action like "Start Activity" in the RunnerUp notification (or on the start button), we can send an intent to the service which in turn sends a message to the wear app. The wear app can then display a custom android activity for an ongoing activity. We can add actions in this activity that will send pause and stop calls back to the main runnerup app.