Improve Upstart enable/disable handling
Improve Upstart enable/disable handling

* Properly search for manual stanza instead of just override
* Handle "manual" stanzas in both override and regular conf files
* Do not try to disable/enable already enabled services
* Do not overwrite override files (use append) on disable
* Only delete empty override files on enable

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt