Changed URLs to https.

The previous version tried to load http content from a page served with https.

_config.yml

@@ -30,6 +30,6 @@ custom_gradle_template: false
 
 ### The following properties are constant for most projects
 
-main_site_url: http://spring.io
+main_site_url: https://spring.io
-projects_site_url: http://projects.spring.io
+projects_site_url: https://projects.spring.io
-questions_url: http://spring.io/questions
+questions_url: https://spring.io/questions

_includes/page.html

@@ -4,7 +4,7 @@
     <link rel="icon" type="image/png" href="{{site.baseurl}}/favicon.png"/>
 
     <link rel="stylesheet" type="text/css" href="{{site.baseurl}}/bootstrap/css/bootstrap.min.css" />
-    <link href='http://fonts.googleapis.com/css?family=Varela+Round|Montserrat:400,700' rel='stylesheet' type='text/css'>
+    <link href='https://fonts.googleapis.com/css?family=Varela+Round|Montserrat:400,700' rel='stylesheet' type='text/css'>
     <link rel="stylesheet" type="text/css" href="{{site.baseurl}}/font-awesome/css/font-awesome.min.css" />
     <link rel="stylesheet" type="text/css" href="{{site.baseurl}}/bootstrap/css/bootstrap-select.css" />