util: Made FileSortOrderByName and FileSortOrderBySize package private.

- Follows principle of least privilege.

src/main/java/com/owncloud/android/utils/FileSortOrderByName.java

@@ -36,7 +36,7 @@ import third_parties.daveKoeller.AlphanumComparator;
  */
 public class FileSortOrderByName extends FileSortOrder {
 
-    public FileSortOrderByName(String name, boolean ascending) {
+    FileSortOrderByName(String name, boolean ascending) {
         super(name, ascending);
     }
 

src/main/java/com/owncloud/android/utils/FileSortOrderBySize.java

@@ -35,7 +35,7 @@ import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 
 public class FileSortOrderBySize extends FileSortOrder {
 
-    public FileSortOrderBySize(String name, boolean ascending) {
+    FileSortOrderBySize(String name, boolean ascending) {
         super(name, ascending);
     }