Build proper TimeZoneInformation strings for upsync; fix bugs

* Create full TZI strings for upload of events (previously, we
  omitted DST information)
* Add documentation to some unit tests
* Put in correct logic for determining if upload needed
* Fix problem w/ parsing empty tags

Change-Id: I268ce8a2db30b3cfdf0e44f6a78befd6bd933243
5 files changed