Instead of always inferring the path at which files in a resource set
are located, let users override the path by specifying a `path` field.
This makes it possible to add the same resource set multiple times
with different values while still keeping distinct names for
addressability (for example when using include/exclude).
This fixes#70
Kontemplate context specifications can now load extra variables from YAML
or JSON files by specifying a list of files (relative to the context file)
under the `import` key.
This adds functionality to specify default values directly in resource sets.
The idea is that users can create a file called `values.yaml` or `values.json`
in a resource set's folder and have all variables specified in that file be
automatically merged into the resource set variables with the lowest priority.
This fixes#25
This fixes#30 (to a degree)
Users of kontemplate may expect variables defined on the parent resource to be
inherited by children.
This implements that functionality. Values defined twice are overwritten by the
child's definition.
Fixes#20
