Adds a time zone parameter to formatDateRange

For a critical feature request in Calendar we need the ability
to format a date range in a time zone other than the local tz.
This adds a new method signature to formatDateRange to allow for
a tz to be specified and maintains the old behavior if the parameter
is not used. Also deprecates the FORMAT_UTC flag.

Change-Id: I16b3e939760ec86c954b51a318d01b7bbf86acc9