Removing excess markup and styles

no longer have tabs in the builder, so removing all that

ui/src/chronograf/components/PanelBuilder.js

@@ -35,14 +35,12 @@ const PanelBuilder = React.createClass({
 
     return (
       <div className="panel-builder" style={{width}}>
-        <div className="panel-builder__tab-content">
-          <div className="panel-builder__item btn btn-block btn-primary" onClick={this.handleCreateExploer}><span className="icon graphline"></span>&nbsp;&nbsp;Create Graph</div>
-          <ExplorerList
-            actions={actions}
-            setActivePanel={this.props.setActivePanel}
-            activePanelID={this.props.activePanelID}
-          />
-        </div>
+        <div className="btn btn-block btn-primary" onClick={this.handleCreateExploer}><span className="icon graphline"></span>&nbsp;&nbsp;Create Graph</div>
+        <ExplorerList
+          actions={actions}
+          setActivePanel={this.props.setActivePanel}
+          activePanelID={this.props.activePanelID}
+        />
       </div>
     );
   },

ui/src/style/chronograf/components/_Explorer.scss

@@ -1,4 +1,3 @@
-
 .explorer {
   display: block;
   background-color: $g3-castle;

ui/src/style/chronograf/components/_PanelBuilder.scss

@@ -2,9 +2,11 @@
   width: 399px;
   overflow-x: hidden;
   background: $g1-raven;
+  padding: $explorer-page-padding;
   @include gradient-v($g2-kevlar,$g0-obsidian);
   @include custom-scrollbar($g2-kevlar,$c-pool);
-}
-.panel-builder__item {
-  margin-bottom: 6px;
+
+  > .btn {
+    margin-bottom: 6px;
+  }
 }