Clean up formatting of numbers in gpx export.

Addresses issue #299 and ensures Latitude and Longitude are formatted
correctly as well.

MyTracksTest/src/com/google/android/apps/mytracks/io/GpxTrackWriterTest.java

@@ -75,12 +75,17 @@ public class GpxTrackWriterTest extends TrackFormatWriterTest {
    * Asserts that the given tag describes the given location.
    */
   private void assertTagMatchesLocation(Element tag, Location loc) {
-    assertEquals(Double.toString(loc.getLatitude()), tag.getAttribute("lat"));
-    assertEquals(Double.toString(loc.getLongitude()), tag.getAttribute("lon"));
+    assertEquals(
+        Location.convert(loc.getLatitude(), GpxTrackWriter.LATLONG_FORMAT),
+        tag.getAttribute("lat"));
+    assertEquals(
+        Location.convert(loc.getLongitude(), GpxTrackWriter.LATLONG_FORMAT),
+        tag.getAttribute("lon"));
     assertEquals(
         GpxTrackWriter.TIMESTAMP_FORMAT.format(new Date(loc.getTime())),
         getChildTextValue(tag, "time"));
-    assertEquals(Double.toString(loc.getAltitude()),
+    assertEquals(
+        GpxTrackWriter.ELEVATION_FORMAT.format(loc.getAltitude()),
         getChildTextValue(tag, "ele"));
   }
 }

MyTracksTest/src/com/google/android/apps/mytracks/io/TrackFormatWriterTest.java

@@ -81,7 +81,7 @@ public abstract class TrackFormatWriterTest extends AndroidTestCase {
   protected void populateLocations(MyTracksLocation... locs) {
     for (int i = 0; i < locs.length; i++) {
       MyTracksLocation loc = locs[i];
-      loc.setAltitude(i * 1000);
+      loc.setAltitude(i * 5000000);
       loc.setLatitude(i);
       loc.setLongitude(-i);
       loc.setTime(10000000 + i * 1000);