First enterprise-compatible sketches, attempt 2

* set_hostname - using strings
* packages_installed - using lists

Also provide constdata.conf for validation use in these sketches.
Resubmitting pull request based on comments from https://github.com/cfengine/design-center/pull/291.

Adjustments:
* use of minimum_value/maximum_value in UID_UNIX and PORT_NUMBER
* changed name and namespace for packages sketch
* removed LIST_OF_STRING_ANY; LIST_OF_STRING_NONEMPTY is the correct