[IMP] all: new design to match the one on odoo.com

* upgrade to bootstrap 3.3.6

* new Header, port website LESS
  - Add the new header
  - Modify sub-header in order to handle “back” button and version
    switcher
  - Port website’s Less:
    * Use same variables’ names
    * Review fonts and colours in order to fit the new style

* add new footer

* Review and optimise JS code in order properly handle the new header,
  footer and card.top animations

* replace  banner images

_extensions/odoo/static/bootstrap-3.3.6/less/thumbnails.less

@@ -0,0 +1,36 @@
+//
+// Thumbnails
+// --------------------------------------------------
+
+
+// Mixin and adjust the regular image class
+.thumbnail {
+  display: block;
+  padding: @thumbnail-padding;
+  margin-bottom: @line-height-computed;
+  line-height: @line-height-base;
+  background-color: @thumbnail-bg;
+  border: 1px solid @thumbnail-border;
+  border-radius: @thumbnail-border-radius;
+  .transition(border .2s ease-in-out);
+
+  > img,
+  a > img {
+    &:extend(.img-responsive);
+    margin-left: auto;
+    margin-right: auto;
+  }
+
+  // Add a hover state for linked versions only
+  a&:hover,
+  a&:focus,
+  a&.active {
+    border-color: @link-color;
+  }
+
+  // Image captions
+  .caption {
+    padding: @thumbnail-caption-padding;
+    color: @thumbnail-caption-color;
+  }
+}