Changed bus stops to use sparse array
Added tracking and uploading of waiting times
Merge branch 'master' of https://github.com/kaiyao/isbtracker2

Conflicts:
	src/com/nus/cs4222/isbtracker/BusStops.java
	src/com/nus/cs4222/isbtracker/WaitingTime.java
	src/com/nus/cs4222/isbtracker/WaitingTimes.java
Removed unused code added during merge.