Remove nagios checks for locations that has changed

[Haw Loeung]

Hi,

When locations for sites are changed, the shipped out nagios check isn't cleaned up. For example:

site1:
  location:
    '/mypath':
      backends:
        - archive.ubuntu.com:80

Then change /mypath to /some-new-path and the nagios checks still exists for /mypath.

[Haw Loeung (hloeung)]

So that's both /etc/nagios/nrpe.d and /var/lib/nagios/export