Switch to Java 7.

Notes regarding Android compatibility:
- The 'try-with-resources' language feature needs API level 19, so don't use it.
  All other language features can be used back to API level 8.
- The JDK 1.7 API still isn't fully implemented, so better stick with 1.6 for now.

enabler/test/de/schildbach/pte/live/VrsProviderLiveTest.java

@@ -511,6 +511,7 @@ public class VrsProviderLiveTest extends AbstractProviderLiveTest {
     }
 
     private static class LocationComparator implements Comparator<Location> {
+        @Override
         public int compare(Location o1, Location o2) {
             return ComparisonChain.start().compare(o1.name, o2.name).result();
         }