settings: Add bootstrap CSS to label.checkbox elements.

This commit adds min-height property added by bootstrap
to the label.checkbox elements in components.css.
We do not need to add padding-left property added by
bootstrap since we already set padding to 0.

After adding this CSS, we can safely remove the CSS from
bootstrap.css.

web/styles/components.css

@@ -7,6 +7,7 @@
         display: inline-block;
         position: relative;
         vertical-align: top;
+        min-height: 20px;
 
         input[type="checkbox"] {
             position: absolute;