Added API client and more

## Proposed changes

- IMDB
  - Added Checkins for Tv series
  - Added Seen ribbon for tv series
- General
  - Adding a personal API-key for use of the extension and adding a library for API calls (based on "Trakt API client for NodeJS", checkin calls are made outside of the library) some communicate directly with the Trakt.tv API
  - Changing option page with "Checkin option toggle" and prefill of apikey/username/password
  - Removed pop-up and browser button (didn't have any function as far as I could see)
  - Made some directories for the source files images/css/js