[schema] drop CWSourceSchemaConfig[cw_for_source,cw_schema] unique constraint (closes #1946277)
as they are not necessarily unique, eg when one want a configuration for both
subject and object
<div id="ajaxroot">
<div class="ajaxHtmlHead">
<script src="http://foo.js" type="text/javascript"> </script>
<link rel="stylesheet" type="text/css" media="all" href="qunit.css" />
</div>
<h1>Hello</h1>
</div>