Fix incorrect array slicing parameters

Ugh I keep getting this error whyyy. I put in 100 LAYERS! 

Well because of a bug.
Array.slice(0, -1) instead of Array.slice(Start at length - 1)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice

src/architecture/architect.js

@@ -274,7 +274,7 @@ const architect = {
       layer_sizes = layer_sizes_and_options;
       options = {};
     } else {
-      layer_sizes = layer_sizes_and_options.slice(layer_sizes_and_options.length - 1);
+      layer_sizes = layer_sizes_and_options.slice(0, -1);
       options = output_size_or_options;
     }