Allow setting of JSON injected values to the raw_value tag for the generated HiddenTextFactory View

[allan-on]

When injecting values into a form by setting the value(s) for hidden fields, for instance by doing valueMap.put("age_in_months", String.valueOf(months)); the values are written into the form JSONObject but aren't set in the (R.id.raw_value) tag for the hidden view generated by the HiddenTextFactory
In effect, this leads to the injected values being overwritten with empty values when saving the form or navigating between steps in the form.
The JsonFormFragmentPresenter#validateAndWriteValues() writes the empty values retrieved at String rawValue = (String) editText.getTag(R.id.raw_value);
Those values are set by a GenericTextWatcherwhich isn't invoked when you inject values prior to loading the form.