Fix the root() function

lib/psd/nodes/ancestry.coffee

@@ -2,7 +2,7 @@ _ = require 'lodash'
 
 module.exports =
   root: ->
-    return @ if isRoot()
+    return @ if @isRoot()
     return @parent.root()
 
   isRoot: -> @depth() is 0
@@ -41,4 +41,4 @@ module.exports =
 
   path: (asArray = false) ->
     path = @ancestors().map((n) -> n.name).concat([@name])
-    if asArray then path else path.join('/')
\ No newline at end of file
+    if asArray then path else path.join('/')