Fix buffering state for live streams
Fix buffering state for live streams

We can't buffer past the live edge, so we must account for the live
edge in buffering state calculations.

Closes #636

Change-Id: I099e68291786a462dfb63471a2eb9974643e75bd

TheModMaker/shaka-player,TheModMaker/shaka-player,Ross-cz/shaka-player,indiereign/shaka-player,Ross-cz/shaka-player,russitto/shaka-player,Ross-cz/shaka-player,brightcove/shaka-player,TobbeEdgeware/shaka-player,russitto/shaka-player,TheModMaker/shaka-player,TobbeEdgeware/shaka-player,TheModMaker/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,vimond/shaka-player,shaka-project/shaka-player,vimond/shaka-player,shaka-project/shaka-player,brightcove/shaka-player,shaka-project/shaka-player,TobbeEdgeware/shaka-player,tvoli/shaka-player,russitto/shaka-player,indiereign/shaka-player,vimond/shaka-player,indiereign/shaka-player,brightcove/shaka-player