icinga: Move naggen into module

- Setup service notification in the file {} definitions,
  and setup a dependency to make sure it executes in order.
  This is more consistent than using subscribes
- Remove the 'permissions fix' code, since all the files
  seem to be generated with appropriate permissions anyway

Change-Id: Icc37c98309b0106de3174a8c39de2c77f50d5652