add newsletter subscription to front page

* and fix focused label

_src/_assets/javascripts/page-front.js

@@ -1,10 +1,9 @@
-
-//=include bigchain/testimonials.js
+//=include bigchain/newsletter.js
 //=include bigchain/github.js
 //=include bigchain/meetup.js
 
 jQuery(function($) {
 
-    Testimonials.init();
+    Newsletter.init()
 
-});
+})

_src/_assets/styles/bigchain/_newsletter.scss

@@ -31,7 +31,8 @@
     }
 
     .form-label,
-    .form-control {
+    .form-control,
+    .form-control:focus ~ .form-label {
         color: $gray-dark;
     }
 

_src/index.html

@@ -68,3 +68,5 @@ intro:
 {% include sections/section-cta-enterprise.html %}
 
 {% include sections/section-blog.html %}
+
+{% include sections/section-newsletter.html %}