Issue VACCUM SQL directive to prevent the DB from keeping old Seeds. (#89)

Issue VACCUM SQL directive to prevent the DB from keeping old Seeds.

Author: pfedan

AuthenticatorApp/src/main/java/com/google/android/apps/authenticator/AccountDb.java

@@ -342,6 +342,7 @@ private static String whereClause(String email) {
 
   public void delete(String email) {
     mDatabase.delete(TABLE_NAME, whereClause(email), null);
+    mDatabase.execSQL("VACUUM");
   }
 
   /**