Major fixes for Song page

Major fixes for Song page

. Changed history link to point to github.
. On the song page, the heading is now fixed to the top part of the page.
  Included in the heading is the home button, the title of the song and
  artist (not linked to show all of the artist's songs) and the HTML5 Audio
  player.
. The bottom part contains the song itself as before. I may add an auto
  scroll option later. It'd be really cool if I could tag the various lines
  and chorus such that the playback syncs with the words but I'm not sure I
  can do that.
. I've added JavaScript to allow the space bar to play/pause playback.
. Added additional keyboard shortcuts for:
  . r - return to start (initially start is 0 but can be set by the "a"
        command)
  . b - rewind back 10 seconds. I choose 10 because that seemed to be a
        good amount to rew/ff. Hit b or f multiple times to go forward or
        backward by 10 secs increments.
  . f - Fast forward 10 seconds.
  . a - Mark start. Say you are listening and playing/singing along with a
        song and you want to practice that part just before the second
        chorus. Well mark that spot with the "a" key. Then play/sing along.
        Didn't get it right? Hit either "r" or the space bar to start at the
        marked position again.
  . c - Clear start. If you don't want that start position anymore clear it
        with "c". Then "r" or space bar will start from 0.
  . ? - Hit "?" to see the keyboard short cuts.