MDL-43738 behat: Refactoring the field type guesser

The previous behaviour delegates the responsability
of overwriting the 3 public methods to the child
classes, now the field type or moodleform field is
guessed earlier in the execution flow.

Other changes introduced here:
- Fix wrong moodleform detection when there is a form
  in the page but the field we are dealing with is
  not inside it.
- Updating the last week feature files to these new
  step definitions.
- Some coding style changes.

lib/behat/form_field/behat_form_radio.php

@@ -89,9 +89,6 @@ class behat_form_radio extends behat_form_checkbox {
      * @return bool
      */
     public function matches($expectedvalue = false) {
-        if (trim($expectedvalue) != trim($this->get_value())) {
-            return false;
-        }
-        return true;
+        return $this->text_matches($expectedvalue);
     }
 }