[sqllab] Added share button to bottom menu (#4584)

* added sharebtn

* address comments

superset/assets/javascripts/SqlLab/components/ShareQuery.jsx

@@ -0,0 +1,22 @@
+import React from 'react';
+
+import CopyToClipboard from '../../components/CopyToClipboard';
+import CopyQueryTabUrl from './CopyQueryTabUrl';
+import Button from '../../components/Button';
+import { t } from '../../locales';
+
+export default class ShareQueryBtn extends CopyQueryTabUrl {
+  render() {
+    return (
+      <CopyToClipboard
+        copyNode={(
+          <Button bsSize="small" className="toggleSave">
+            <i className="fa fa-clipboard" /> {t('Share Query')}
+          </Button>
+      )}
+        tooltipText={t('copy URL to clipboard')}
+        shouldShowText={false}
+        getText={this.getUrl.bind(this)}
+      />);
+  }
+}