Allow item stacks as input for recipes

* Create the SlotController and refactor it into the various places
  where a crafting grid or crafting output is displayed
* Update the Recipe model to allow each "input" stack to retain the
  count indicated in the data file. This required changing how a few
  other classes interact with it in order for them to get the full
  stack back again for each input (instead of just getting the item
  slug)
* Update the ModVersionParser to allow for full stacks to be given
  as input and refactored common code out for handling input/output/
  tools stacks

src/scss/templates/index.scss

@@ -26,5 +26,6 @@ All rights reserved.
 @import 'mod_page';
 @import 'mod_selector';
 @import 'stack';
+@import 'slot';
 @import 'tutorial';
 @import 'video';

src/scss/templates/slot.scss

@@ -0,0 +1,18 @@
+/*
+Crafting Guide - slot.scss
+
+Copyright (C) 2015 by Redwood Labs
+All rights reserved.
+*/
+
+.view__slot {
+    position: relative;
+
+    .quantity {
+        position: absolute; right: 0.1em; bottom: 0;
+        color: white;
+        font-family: $font-family-header;
+        font-size: $font-size-large;
+        text-shadow: -2px -2px 0 #000, 2px -2px 0 #000, -2px 2px 0 #000, 2px 2px 0 #000;
+    }
+}