Added recordExtras to record data structure.
Implemented SoundCloud player. Styling needs to be refined.
Styled soundcloud player.
Merge branch 'soundcloud-player'

Implemented the SoundCloud player.
At pageload, both SC and YT players are loaded.
The active one is visible, due to opacity "1".
The inactive one is invisible, due to opacity "0".
Also, the inactive one is unclickable, due to z-index "-1".