The hierarchy for loading variables was previously not expressed
explicitly.
This commit refactors the logic for merging variables to explicitly
set the different layers of variables as values on the context object
and merge them for each resource set in `mergeContextValues`.
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
