Update dependency Arbre to version 1.0.1

Author: pcreux

activeadmin.gemspec

@@ -27,5 +27,5 @@ Gem::Specification.new do |s|
   s.add_dependency("kaminari", ">= 0.13.0")
   s.add_dependency("sass", ">= 3.1.0")
   s.add_dependency("fastercsv", ">= 0")
-  s.add_dependency("arbre", ">= 1.0.0.rc4")
+  s.add_dependency("arbre", ">= 1.0.1")
 end