Add nascent version of the mod detail page

* Create a nascent version of the mod detail page
* Make the slug mandatory for Mod instead of name, and load the name
  from the data file
* Make the Feedback view universal on all pages
* Refactor the use of mod pack to have a single global object at the
  router level which is shared between pages. Further, make this one
  object load itself immediately and have it automatically load any
  activated mod version
* Refactor the use of Storage related to mod pack versions into the
  router as well.
* Add trace logging back in for events, but allow individual classes
  to suppress it (as opposed to actually supressing the events)
* Fix a bug in ModVersion.eachItem where it would suggest so-called
  items which are merely registered slugs without associated items

src/scripts/models/mod_pack.coffee

@@ -78,6 +78,7 @@ module.exports = class ModPack extends BaseModel
     # Property Methods #############################################################################
 
     addMod: (mod)->
+        if not mod? then throw new Error 'mod is required'
         return if @_mods.indexOf(mod) isnt -1
 
         @_mods.push mod
@@ -94,6 +95,11 @@ module.exports = class ModPack extends BaseModel
         for mod in @_mods
             callback mod
 
+    getMod: (slug)->
+        for mod in @_mods
+            return mod if mod.slug is slug
+        return null
+
     getMods: ->
         return @_mods[..]