Creates a new computer invitation by invitation

<computer_invitation>
	<invitation_type>DEFAULT</invitation_type>
	<expiration_date>2012-12-07 11:13:35</expiration_date>
	<ssh_username>jamfadmin</ssh_username>
	<ssh_password>accountpassword</ssh_password>
	<multiple_uses_allowed>false</multiple_uses_allowed>
	<create_account_if_does_not_exist>false</create_account_if_does_not_exist>
	<hide_account>false</hide_account>
	<lock_down_ssh>false</lock_down_ssh>
	<enroll_into_site>
		<id>-1</id>
		<name>None</name>
	</enroll_into_site>
	<keep_existing_site_membership>false</keep_existing_site_membership>
	<site>
		<id>-1</id>
		<name>None</name>
	</site>
</computer_invitation>