Bugfix: $bind_ip is not taken in account on Debian systems provisioned with the 10gen/mongodb repository

MongoDB servers installed on Debian systems from the 10gen/mongodb repository only listen on the loopback interface, even if the $bind_ip parameter is defined.

To reproduce:
```puppet
class {'mongodb::globals':
  manage_package_repo => true,
  server_package_name => "mongodb-org-server", 
  version => '2.6.5',
  bind_ip => ['127.0.0.1', $::ipaddress],
} ->
class {'mongodb::server': }
```