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/alerts.less

@@ -0,0 +1,70 @@
+// ALERT STYLES
+// ------------
+
+// Base alert styles
+.alert {
+  padding: 8px 35px 8px 14px;
+  margin-bottom: @baseLineHeight;
+  text-shadow: 0 1px 0 rgba(255,255,255,.5);
+  background-color: @warningBackground;
+  border: 1px solid @warningBorder;
+  .border-radius(4px);
+}
+.alert,
+.alert-heading {
+  color: @warningText;
+}
+
+// Adjust close link position
+.alert .close {
+  position: relative;
+  top: -2px;
+  right: -21px;
+  line-height: 18px;
+}
+
+// Alternate styles
+// ----------------
+
+.alert-success {
+  background-color: @successBackground;
+  border-color: @successBorder;  
+}
+.alert-success,
+.alert-success .alert-heading {
+  color: @successText;
+}
+.alert-danger,
+.alert-error {
+  background-color: @errorBackground;
+  border-color: @errorBorder;
+}
+.alert-danger,
+.alert-error,
+.alert-danger .alert-heading,
+.alert-error .alert-heading {
+  color: @errorText;
+}
+.alert-info {
+  background-color: @infoBackground;
+  border-color: @infoBorder;
+}
+.alert-info,
+.alert-info .alert-heading {
+  color: @infoText;
+}
+
+
+// Block alerts
+// ------------------------
+.alert-block {
+  padding-top: 14px;
+  padding-bottom: 14px;
+}
+.alert-block > p,
+.alert-block > ul {
+  margin-bottom: 0;
+}
+.alert-block p + p {
+  margin-top: 5px;
+}