zypper: Fix gpg check option for state=latest. --no-gpg-checks is used in new and old zypper versions

Bugfix for gpg check in the zypper module https://github.com/ansible/ansible-modules-extras/issues/154

For the state=latest was the gpg check missing.


The option to disable gpg check is the same for zypper <1 and >1

Have a look on the man-page:
zypper version <1
https://en.opensuse.org/Archive:Zypper_usage_11.0#No_GPG_Checks_Mode
zypper version >1
http://wiki.linux-club.de/opensuse/Man_zypper