In some cases, underscores in lang codes get replaced with dashes
which causes some JavaScript to be unhappy. This patch simply reverse
the underscore to dash replacement on the JS side.
Now the db/service.php array can contain these extra keys to provide information
on how a webservice may be called:
'ajax' => true (Default is false)
Replaces the xx_is_allowed_from_ajax callback.
'loginrequired' => false (Default is true)
Means that this webservice can be called through lib/ajax/service-nosession.php
which sets NO_MOODLE_COOKIES to true (faster). This is only safe for webservices returning
static public data (e.g. get_string).
