Fix parser comment about the required fields
Remove unused function
Fix daylight savings time test for non-EST/EDT zones

time.Parse("Mon Jan 2 15:04 2006 MST", "Sun Mar 11 00:00 2012 EST") in
non-EST/EDT zone returns +0000 as offset. Changed to use ISO 8601 format
with a location set to America/New_York.
Merge pull request #2 from tilinna/master

Some comment and test fixes