api: method_missing doesnt resolve hashmaps

Since #its has its(pun) own way of handling calls with a dot-notation, the full call is never passed to the resource. For example:

```ruby
describe json('file') do
  its('a.b.c') { should eq 123 }
end
```

This is resolved to calling `json('file').a.b.c` and thus doesnt work as an intended `json('file').send('a.b.c'). For now use
regular its-behavior of calling `json('file').params ...  its(%w{a b c}) { should ... }`.

Its' behavior must be improved.

lib/resources/json.rb

@@ -49,10 +49,13 @@ class JsonConfig < Inspec.resource(1)
     end
   end
 
+  # Shorthand to retrieve a parameter name via `#its`.
+  # Example: describe json('file') { its('paramX') { should eq 'Y' } }
+  #
+  # @param [String] name name of the field to retrieve
+  # @return [Object] the value stored at this position
   def method_missing(name)
-    # split dotted path
-    keys = name.to_s.split('.')
-    extract_value(keys, @params.clone)
+    @params[name.to_s]
   end
 
   def to_s