Help text

http://manage.dimagi.com/default.asp?130862#777250

http://manage.dimagi.com/default.asp?141280
Rather than using the hard-coded value here, I think this should use the form ID (same as above) now that we've figured out how to get that. `itextMediaWidget` should allow a second (optional) argument that when provided adds an extra qualifier to the label. In this case you'll pass in `"help"`
```js
block.itextWidget = itextMediaWidget(mug.getFormPath(), "help");
```
and the media URL will become

`jr://file/commcare/<form>/<url-type>/<default-itext-root>-help.<extension>`