Fix jeffp123#3

Add guard of zero or negative num in String.repeat(num)
so it won't crash on long words.

content/js/spray-reader.js

@@ -153,5 +153,5 @@ function pivot(word){
 // Let strings repeat themselves,
 // because JavaScript isn't as awesome as Python.
 String.prototype.repeat = function( num ){
-    return new Array( num + 1 ).join( this );
+    return (num<=0) ? "" : new Array( num + 1 ).join( this );
 }