Removed some subreddits from list of default subreddits because they are barely active.

Content of those barely active subreddits rarely changed so we always
so the same stuff from them.
Updated “Features“ section of README.
Styled the message that users with disabled JavaScript see.
JavaScript libraries (AngularJS, JQuery) are now loaded from Google’s CDN. <noscript> message now lists the URLs to unblock and why they are needed.
Removed AngularJS and JQuery library files since we now load them from Google’s CDN.