Adding custom 404 page

Automatically redirects if a page differing only in case is found.

404.html

@@ -0,0 +1,34 @@
+---
+layout: page
+title: 404 Page Not Found
+---
+<script>
+var allposts = [];  
+function redirectToCorrectPage() {
+	{% for post in site.pages %}  
+		allposts.push("{{ post.url }}");  
+	{% endfor %}  
+	{% for post in site.wikis %}  
+		allposts.push("{{ post.url }}");  
+	{% endfor %}  
+	var url = window.location.pathname;
+	// strip trailing /
+	if (url.slice(-1) === "/") {  
+		 url = url.slice(0, -1);  
+	}
+	var allpostsUpperCase = allposts.map(function(value) {  
+	  // strip trailing /
+	  if (value.slice(-1) === "/") {  
+		  value = value.slice(0, -1);  
+	  }
+		return value.toUpperCase();  
+	});  
+	var i = allpostsUpperCase.indexOf(url.toUpperCase());  
+	if (i != -1) {  
+		console.log(allposts[i]);  
+		window.location = allposts[i];  
+	}  
+}  
+window.onload = redirectToCorrectPage;
+</script>
+<p>Sorry this page does not exist =(</p>

_config.yml

@@ -83,3 +83,4 @@ defaults:
       path: "" # empty string for all files
     values:
       layout: page
+