Add modman support for Mandrill and fix some dependency issues

Move the autoresponder observer from Mandrill module to
Autoresponder module to avoid having a dependency from
Mandrill to Autoresponder

Add top nav menu to get to Mandrill settings from Newsletter
menu.  This is probably just a good idea in general, but specifically
when only installing the Mandrill module, the "monkey" tab
which it uses for it's config isn't available.

Create modman file for Mandrill module
resolve conflict with autoresponder config. modman covered in other PR
Merge branch 'kalenjordan-master' into develop