Quick start overhaul.

- Overhauled the concepts/overview section.
- Removed the use of embedded keys in license tokens. Using key seeds is now the implicit recommended default process.
- License tokens now utilize Entitlement Message v2.
- Replaced demo players with just Shaka player, that also includes FairPlay integration (Fixes #23).
- Demo player should now list only platform-compatible demo videos.
- Added multi-key scenario (Fixes #18)
- Terminology changes (Key Server -> Key Service, License Server -> License Service, Authorization Service -> Secure Token Service, etc)
- Readme images, diagrams, text updated to reflect the latest state.
- Other readme improvements.

Author: Heronyme

CatalogApi.js

@@ -16,10 +16,12 @@
 				let videoList = [];
 
 				videoDatabase.getAllVideos().forEach(function mapVideo(video) {
-					// Only name and URL are exposed to the browser. Everything else is for internal use only.
+					// Only name, URL and an optional list tags are exposed to the browser.
+					// Everything else is for internal use only.
 					videoList.push({
 						"name": video.name,
-						"url": video.url
+						"url": video.url,
+						"tags": video.tags
 					});
 				});