Remove all frameworks except Bootstrap (#251)

- Remove all frameworks except Bootstrap

- Remove roots-options.php and replace with a more simple
  roots-config.php

- Include all Bootstrap Javascript plugins by default in
  js/plugins.js

- Use Bootstrap Responsive and Topbar navigation by default

- Use Bootstrap markup on forms, page titles, image galleries,
  alerts and errors, post and comment navigation

- Remove Roots styles from style.css and introduce app.css for
  site-specific CSS. Remove almost all previous default Roots
  styles.

- Add latest updates from H5BP project

css/less/utilities.less

@@ -0,0 +1,23 @@
+// UTILITY CLASSES
+// ---------------
+
+// Quick floats
+.pull-right {
+  float: right;
+}
+.pull-left {
+  float: left;
+}
+
+// Toggling content
+.hide {
+  display: none;
+}
+.show {
+  display: block;
+}
+
+// Visibility
+.invisible {
+  visibility: hidden;
+}