Fix margin for adblack settings + site exceptions

Test Plan: Make sure with site exceptions (like turning off adblock in
the bravery panel of a site), that it displays correctly and not glued.

For a screenshot see the parent issue.

Fix #4503

Auditors: @bsclifton

js/about/preferences.js

@@ -1158,11 +1158,13 @@ class ShieldsTab extends ImmutableComponent {
         <SettingCheckbox checked={this.props.braveryDefaults.get('safeBrowsing')} dataL10nId='safeBrowsing' onChange={this.onToggleSafeBrowsing} />
         <SettingCheckbox checked={this.props.braveryDefaults.get('noScript')} dataL10nId='noScript' onChange={this.onToggleNoScript} />
         <SettingCheckbox dataL10nId='blockCanvasFingerprinting' prefKey={settings.BLOCK_CANVAS_FINGERPRINTING} settings={this.props.settings} onChangeSetting={this.props.onChangeSetting} />
+        <SettingItem>
+          <Button l10nId='manageAdblockSettings' className='primaryButton manageAdblockSettings'
+            onClick={aboutActions.newFrame.bind(null, {
+              location: 'about:adblock'
+            }, true)} />
+        </SettingItem>
       </SettingsList>
-      <Button l10nId='manageAdblockSettings' className='primaryButton manageAdblockSettings'
-        onClick={aboutActions.newFrame.bind(null, {
-          location: 'about:adblock'
-        }, true)} />
       <SitePermissionsPage siteSettings={this.props.siteSettings}
         names={braveryPermissionNames}
         defaults={this.props.braveryDefaults.merge({

less/about/preferences.less

@@ -445,6 +445,10 @@ span.browserButton.primaryButton {
     .checkboxContainer {
       width: 100px;
     }
+
+    .manageAdblockSettings {
+      margin-top: 1em;
+    }
   }
 
   .subtext {