Delete rows and add instead of updating
Moved loadSchedule method inside asynctask

/src/org/osuosl/ocw/Schedule.java: The necessary logic used in loadSchedule is now inside the load and refresh asynctasks. Added a null and isEmpty check on DAYS in onCreate as when switching days using the day list would create a new DAYS object.
Merge pull request #33 from markholland/bug-14973

Bug 14973