Added logic to enable querying for most recent UV Irradiance data
Added inside of SunUtil updateUVI() a method to compute the mean UVI from parse.com table
Added Timer object (which I decided not to use) to periodically update the UVI readings.
	Don't use the timer cause each segment instance instantiates a SunUtil Class just do do single computation. When finished the class deletes itself. Therefore, I don't think we need a timer (as of now).