use custom checkbox images (material design) while toggling

src/com/owncloud/android/ui/adapter/FileListListAdapter.java

@@ -211,10 +211,10 @@ public class FileListListAdapter extends BaseAdapter implements ListAdapter {
                             } else {
                                 if (parentList.isItemChecked(position)) {
                                     checkBoxV.setImageResource(
-                                            android.R.drawable.checkbox_on_background);
+                                            R.drawable.ic_checkbox_marked);
                                 } else {
                                     checkBoxV.setImageResource(
-                                            android.R.drawable.checkbox_off_background);
+                                            R.drawable.ic_checkbox_blank_outline);
                                 }
                                 checkBoxV.setVisibility(View.VISIBLE);
                             }

src/com/owncloud/android/ui/adapter/LocalFileListAdapter.java

@@ -124,9 +124,9 @@ public class LocalFileListAdapter extends BaseAdapter implements ListAdapter {
                     checkBoxV.setVisibility(View.GONE);
                 } else {
                     if (parentList.isItemChecked(position)) {
-                        checkBoxV.setImageResource(android.R.drawable.checkbox_on_background);
+                        checkBoxV.setImageResource(R.drawable.ic_checkbox_marked);
                     } else {
-                        checkBoxV.setImageResource(android.R.drawable.checkbox_off_background);
+                        checkBoxV.setImageResource(R.drawable.ic_checkbox_blank_outline);
                     }
                     checkBoxV.setVisibility(View.VISIBLE);
                 }

src/com/owncloud/android/ui/fragment/LocalFileListFragment.java

@@ -120,9 +120,9 @@ public class LocalFileListFragment extends ExtendedListFragment {
                 ImageView checkBoxV = (ImageView) v.findViewById(R.id.custom_checkbox);
                 if (checkBoxV != null) {
                     if (((ListView)getListView()).isItemChecked(position)) {
-                        checkBoxV.setImageResource(android.R.drawable.checkbox_on_background);
+                        checkBoxV.setImageResource(R.drawable.ic_checkbox_marked);
                     } else {
-                        checkBoxV.setImageResource(android.R.drawable.checkbox_off_background);
+                        checkBoxV.setImageResource(R.drawable.ic_checkbox_blank_outline);
                     }
                 }
                 // notify the change to the container Activity