[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/jumbotron.less

@@ -0,0 +1,54 @@
+//
+// Jumbotron
+// --------------------------------------------------
+
+
+.jumbotron {
+  padding-top:    @jumbotron-padding;
+  padding-bottom: @jumbotron-padding;
+  margin-bottom: @jumbotron-padding;
+  color: @jumbotron-color;
+  background-color: @jumbotron-bg;
+
+  h1,
+  .h1 {
+    color: @jumbotron-heading-color;
+  }
+
+  p {
+    margin-bottom: (@jumbotron-padding / 2);
+    font-size: @jumbotron-font-size;
+    font-weight: 200;
+  }
+
+  > hr {
+    border-top-color: darken(@jumbotron-bg, 10%);
+  }
+
+  .container &,
+  .container-fluid & {
+    border-radius: @border-radius-large; // Only round corners at higher resolutions if contained in a container
+    padding-left:  (@grid-gutter-width / 2);
+    padding-right: (@grid-gutter-width / 2);
+  }
+
+  .container {
+    max-width: 100%;
+  }
+
+  @media screen and (min-width: @screen-sm-min) {
+    padding-top:    (@jumbotron-padding * 1.6);
+    padding-bottom: (@jumbotron-padding * 1.6);
+
+    .container &,
+    .container-fluid & {
+      padding-left:  (@jumbotron-padding * 2);
+      padding-right: (@jumbotron-padding * 2);
+    }
+
+    h1,
+    .h1 {
+      font-size: @jumbotron-heading-font-size;
+    }
+  }
+}