Center location maker in bottom half of screen in routing mode

Re-center map to point ahead of location marker in routing mode.

Closes #105

app/src/main/kotlin/com/mapzen/erasermap/view/RouteModeView.kt

@@ -1,13 +1,15 @@
 package com.mapzen.erasermap.view
 
 import android.content.Context
+import android.graphics.Point
 import android.location.Location
 import android.support.v4.view.PagerAdapter
 import android.support.v4.view.ViewPager
 import android.util.AttributeSet
 import android.view.LayoutInflater
 import android.view.MotionEvent
 import android.view.View
+import android.view.WindowManager
 import android.widget.Button
 import android.widget.ImageView
 import android.widget.LinearLayout
@@ -313,6 +315,19 @@ public class RouteModeView : LinearLayout, RouteViewController, ViewPager.OnPage
         mapController?.mapRotation = getBearingInRadians(location)
         mapController?.mapZoom = MainPresenter.ROUTING_ZOOM
         mapController?.mapTilt = MainPresenter.ROUTING_TILT
+        adjustMapPosition()
+    }
+
+    private fun adjustMapPosition() {
+        val windowManager = context.getSystemService(Context.WINDOW_SERVICE) as WindowManager
+        val display = windowManager.defaultDisplay
+        val point = Point()
+        display.getSize(point)
+
+        val x = point.x/2
+        val y = point.y/4
+        val position = mapController?.coordinatesAtScreenPosition(x.toDouble(), y.toDouble())
+        mapController?.mapPosition = position
     }
 
     override fun updateSnapLocation(location: Location) {