[explore-v2] control panel fixes (#1529)

* make fieldset conditions more clear

* make label required

* use render* pattern

* use slugify util for turning labels into ids

* use field rather than html

* don't need panel-title class here

caravel/assets/javascripts/components/InfoTooltipWithTrigger.jsx

@@ -1,5 +1,6 @@
 import React, { PropTypes } from 'react';
 import { Tooltip, OverlayTrigger } from 'react-bootstrap';
+import { slugify } from '../modules/utils';
 
 const propTypes = {
   label: PropTypes.string.isRequired,
@@ -10,7 +11,7 @@ export default function InfoTooltipWithTrigger({ label, tooltip }) {
   return (
     <OverlayTrigger
       placement="right"
-      overlay={<Tooltip id={`${label}-tooltip`}>{tooltip}</Tooltip>}
+      overlay={<Tooltip id={`${slugify(label)}-tooltip`}>{tooltip}</Tooltip>}
     >
       <i className="fa fa-question-circle-o" />
     </OverlayTrigger>