Update cli.py

[benbugohit]

Add deleteMissing option as described in zabbix 4.0 api documentation:
https://www.zabbix.com/documentation/4.0/manual/api/reference/configuration/import

[paalbra]

As far as I can tell there is no bug here. This PR would break current behavior (since it's altering the default).

It would be nice if the command supported this as parameters I suppose, but that would require more work.

[benbugohit]

It's not about a bug, but about a feature :) since deleteMissing option is supported in zabbix 3.0 API also.
IMO default behavior is inconsistent concerning not deleting missing applications/items/triggers in newly imported templates:
It doesn't clean up configuration in my use case.
Concerning the option, it's a good idea.
As an example, it's available in this other project:
https://github.com/q1x/zabbix-gnomes/blob/master/ztmplimport.py
starting line 123

[paalbra]

I've created this enhancement as a new issue #114 . I'm closing this PR since a merge would alter the current behavior.

Feel free to add comments in the new issue.