UOFLMA-96: Changed dialog string.

app/src/main/java/com/vsoft/uoflservicenow/ui/CatalogueVariableScreen.java

@@ -864,7 +864,7 @@ public class CatalogueVariableScreen extends AppCompatActivity {
         AlertDialog.Builder builder = new AlertDialog.Builder(this);
         builder.setMessage(R.string.variable_form_back_navigation_string)
                 .setCancelable(false)
-                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                .setPositiveButton(R.string.yes_string, new DialogInterface.OnClickListener() {
                     public void onClick(DialogInterface dialog, int id) {
                         finish();
                     }