Update URLs in GitHub Pages (#2953)

Project is now under https://github.com/jerryscript-project and
https://jerryscript.net . Update hardcoded URLs to use HTTPS, both
for JerryScript and IoT.js. Make non-hardcoded URLs use Jekyll's
`relative_url` filter to avoid mixed content errors on GH Pages.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

_layouts/default.html

@@ -15,7 +15,7 @@
 
     <!-- Bootstrap core JavaScript -->
     <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
-    <script src="{{ site.github.url }}/js/bootstrap.min.js"></script>
+    <script src="{{ '/js/bootstrap.min.js' | relative_url }}"></script>
 
   </body>
 </html>