Move more system contact info into recipient database

1) Move contact URI, contact photo URI, and custom label
   into recipient database, so there are no longer any
   contact DB queries during Recipient object loading.

2) Use a SoftHashMap so that any referenced Recipient objects
   can't get kicked out of the cache.

3) Don't load Recipient objects through the provider during sync.
   This was a super expensive thing to do, and blew up the cache.

4) Only apply changes to Recipient objects during sync if they
   are in the cache. Otherwise, there should be no outstanding
   references, and the changes are fine going exclusively to
   the DB.

src/org/thoughtcrime/securesms/contacts/ContactAccessor.java

@@ -79,7 +79,7 @@ public class ContactAccessor {
   }
 
   public Cursor getAllSystemContacts(Context context) {
-    return context.getContentResolver().query(Phone.CONTENT_URI, new String[] {Phone.NUMBER, Phone.DISPLAY_NAME}, null, null, null);
+    return context.getContentResolver().query(Phone.CONTENT_URI, new String[] {Phone.NUMBER, Phone.DISPLAY_NAME, Phone.LABEL, Phone.PHOTO_URI, Phone._ID, Phone.LOOKUP_KEY}, null, null, null);
   }
 
   public boolean isSystemContact(Context context, String number) {