Report last known location when engine enabled

[sarahsnow1]

Overview

This PR updates the FusionEngine to check for a last known location for each enabled location provider and return that location if it exists.

Proposed Changes

Here is example output from these two test classes used

FusedLocationActivity

12-06 15:53:11.558 1765-1765/com.mapzen.googleplayservicestest D/Test: onConnected
12-06 15:53:11.568 1765-1765/com.mapzen.googleplayservicestest D/Test: last known network
12-06 15:53:11.568 1765-1765/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:network bearing:0.0 nanos:6514803000000 speed:0.0 time:1481064657644
12-06 15:53:11.568 1765-1765/com.mapzen.googleplayservicestest D/Test: lastKnownLocation
12-06 15:53:11.568 1765-1765/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:fused bearing:0.0 nanos:6648737000000 speed:0.0 time:1481064791578
12-06 15:53:11.578 1765-1765/com.mapzen.googleplayservicestest D/Test: Location Changed
12-06 15:53:11.578 1765-1765/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:fused bearing:0.0 nanos:6648746000000 speed:0.0 time:1481064791587

LostFusedLocationActivity

12-06 15:50:57.598 30873-30873/com.mapzen.googleplayservicestest D/Test: onConnected
12-06 15:50:57.598 30873-30873/com.mapzen.googleplayservicestest D/Test: last known network
12-06 15:50:57.598 30873-30873/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:network bearing:0.0 nanos:6477295000000 speed:0.0 time:1481064620137
12-06 15:50:57.598 30873-30873/com.mapzen.googleplayservicestest D/Test: lastKnownLocation
12-06 15:50:57.598 30873-30873/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:network bearing:0.0 nanos:6477295000000 speed:0.0 time:1481064620137
12-06 15:50:57.608 30873-30873/com.mapzen.googleplayservicestest D/Test: Location Changed
12-06 15:50:57.608 30873-30873/com.mapzen.googleplayservicestest D/Test: ch acc:2198.0 lat:40.0173948 lng:-105.3028802 provider:network bearing:0.0 nanos:6477295000000 speed:0.0 time:1481064620137

FusedLocationActivity.txt
LostFusedLocationActivity.txt

Closes #141

[ecgreb]

For location requests with PRIORITY_HIGH_ACCURACY this method would be invoked for both GPS_PROVIDER and NETWORK_PROVIDER resulting in two initial location updates.

We should only send one initial location update and use the logic in FusionEngine.getLastLocation() to decide which one is best.