Install object-expirer on admin box (issue 126)

* Added new recipe and updated controller role

* Fixes issue 126

* Disables proxy-server and object-server on admin node, as these are
  unwanted services but centos and ubuntu package object-expirer with
  them.

* Deletes proxy-server.conf and object-server.conf on admin node to
  keep swift-init from starting these unwanted services.