Added support for "hidden" property in the manifest.json. A hidden package will be enabled, but not appear in the Kinds/Modules/Index/Packages lists. This allows you to show only the specific packages you want, but still show inherited kinds/functions from hidden packages that may be subkinded.

For example, you could mark "enyo" as "hidden":true, and then onyx.Button would still show all inherited functions and allow inline access to enyo.Button and its superkinds, without the added clutter on the left-hand panels.
Merge pull request #17 from JayCanuck/master

Adds support for "hidden" property in the manifest.json

Reviewed-By: Ben Combee (ben.combee@lge.com)