enable https on all the URLs that can be

Author: Thomas Grainger

_sections/50-why.md

@@ -15,5 +15,5 @@ code to use Python 3:
 - [How to add Python 3 support to your code](https://docs.python.org/3/howto/pyporting.html)
 - [Stop supporting Python 2.6 for free](http://www.curiousefficiency.org/posts/2015/04/stop-supporting-python26.html) (Nick Coghlan)
 - [Why Python 4.0 won't be like Python 3.0](http://www.curiousefficiency.org/posts/2014/08/python-4000.html) (Nick Coghlan)
-- [Python 3 for scientists](http://python-3-for-scientists.readthedocs.io/en/latest/)
+- [Python 3 for scientists](https://python-3-for-scientists.readthedocs.io/en/latest/)
 - [scikit-bio py3-only RFC](https://github.com/biocore/scikit-bio-rfcs/blob/master/accepted/002-py3-only.md)

index.html

@@ -9,10 +9,10 @@
 	<meta name="keywords" content="{{ site.keywords }}">
 	<meta name="description" content="{{ site.description }}">
   <link rel="stylesheet" href="combo.css">
-  <link href='//fonts.googleapis.com/css?family=Raleway:400,300,700' rel='stylesheet' type='text/css'>
-  <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css">
-  <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/vis/4.16.1/vis.min.css">
-  <script src="//cdnjs.cloudflare.com/ajax/libs/vis/4.16.1/vis.min.js"></script>
+  <link href='https://fonts.googleapis.com/css?family=Raleway:400,300,700' rel='stylesheet' type='text/css'>
+  <link rel="stylesheet" href="https://netdna.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css">
+  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/vis/4.16.1/vis.min.css">
+  <script src="https://cdnjs.cloudflare.com/ajax/libs/vis/4.16.1/vis.min.js"></script>
   {% if site.favicon %}<link rel="shortcut icon" href="{{ site.favicon }}" type="image/x-icon">{% endif %}
 	{% if site.touch_icon %}<link rel="apple-touch-icon" href="{{ site.touch_icon }}">{% endif %}
 </head>