Added putter and getter for shared preferences
Added onResume method
Save timeout and last updated to sharedPrefs
Load timeout, lastUpdated from sharedPrefs instead of database
In onResume check for timeout
If timeout onResume then load from server

/src/org/osuosl/ocw/Schedule.java: Made data a global variables to know whether onResume is called on a orientation switch. Check if timeout has hit when onResume and then proceed to force load data from server.
Removed passing global variable calendar as parameter

/src/org/osuosl/ocw/Schedule.java
Check json http header before updating

/src/org/osuosl/ocw/Schedule.java: Added date formatter for http headers. Added view refresh in onResume when a timeout has hit. Added do nothing return on getURL for when the json hasn't been updated. Added jsonModified that returns whether a json file has been modified.