Refactor testsuite config stuff

This generalizes copying a test's "etc/" data and templating
  files ending in .tmpl, which will make it easier to test
  some other upcoming features...
Implement config includefiles at the vscf layer.

What this solution gives us (which is pretty useful):
  1) The ability to have the included file be a set of
    hash mappings that are merged into a hash in the parent
    file.
  2) The ability to have the included file be a whole hash
    or array that's used as a single value in the parent file.

What it doesn't give us:
  1) You can't use the include mechanism to merge a child-file's
    top-level array into an existing array in the parent.
  2) You can't use the include mechanism to specify a singular
    value in a child-file.

Notably, this extends includefile powers to other consumers of
  vscf within the code, such as the "nets" file for the geoip
  plugin.  However, the geoip plugin reloads the "nets" data on
  stat(2) changes, and that reload mechanism won't extend to a
  change in just the child file.  vscf's current API really
  doesn't have the power to offer that.

I still think something like Lua is better than vscf in the long
  run, and I think that will become more apparent every time we
  want to add yet another deeper language feature to vscf, but
  this helps for now.