Fix spec test of feature api

[lbetz]

expected that the catalogue would contain Exec[icinga2 pki create key] with command set to "/usr/local/sbin/icinga2 pki new-cert --cn host.example.org --key /var/lib/icinga2/certs/host.example.org.key --cert /var/lib/icinga2/certs/host.example.org.crt" but it is set to ""/usr/local/sbin/icinga2" pki new-cert --cn host.example.org --key /var/lib/icinga2/certs/host.example.org.key --cert /var/lib/icinga2/certs/host.example.org.crt"

quoting of icinga2 binary was new in v2.1.0