fix  call of 'create_database' if db not exists.

without this change thrown:
postgres_plugin.rb:187:in `create_database': wrong number of arguments (4 for 6) (ArgumentError)
	from /vagrant/hanlon/core/persist/postgres_plugin.rb:42:in `rescue in connect'
	from /vagrant/hanlon/core/persist/postgres_plugin.rb:38:in `connect'
	from /vagrant/hanlon/core/persist/controller.rb:74:in `connect_database'
	from /vagrant/hanlon/core/persist/controller.rb:66:in `check_connection'
	from /vagrant/hanlon/core/persist/controller.rb:44:in `initialize'