A resource set collection is a resource set with an addition 'include' array
configured. It is a short-hand for importing multiple resource sets from the
same folder and for excluding/including them as a group.
See https://github.com/tazjin/kontemplate/issues/9 for more information.
Closes#9
Adds a basic CLI structure with a single "run" command that takes a --file (-f)
and --limit (-l) flag.
--limit can be used to only output certain resource sets.
Closes#4