Fix macro load

Author: alexandermeindl

lib/redmine_ref_issues.rb

@@ -5,11 +5,11 @@ module RedmineRefIssues
 
   class << self
     def setup
-      Dir[Redmine::Plugin.find(:redmine_ref_issues).directory,
-          'lib',
-          'redmine_ref_issues',
-          'wiki_macros',
-          '**/*_macro.rb'].sort.each { |f| require f }
+      Dir[File.join(Redmine::Plugin.find(:redmine_ref_issues).directory,
+                    'lib',
+                    'redmine_ref_issues',
+                    'wiki_macros',
+                    '**/*_macro.rb')].sort.each { |f| require f }
     end
 
     def cast_table_field(db_table, db_field)