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/scaffolding.less

@@ -0,0 +1,29 @@
+// Scaffolding
+// Basic and global styles for generating a grid system, structural layout, and page templates
+// -------------------------------------------------------------------------------------------
+
+
+// STRUCTURAL LAYOUT
+// -----------------
+
+body {
+  margin: 0;
+  font-family: @baseFontFamily;
+  font-size: @baseFontSize;
+  line-height: @baseLineHeight;
+  color: @textColor;
+  background-color: @white;
+}
+
+
+// LINKS
+// -----
+
+a {
+  color: @linkColor;
+  text-decoration: none;
+}
+a:hover {
+  color: @linkColorHover;
+  text-decoration: underline;
+}