Time tests and fixes.

This adds tests for the time specifiers (including with all the previous
date tests). Combined this brings the tests up to ~360k with 88% lines
covered.

Statements   : 88.52% ( 1782/2013 )
Branches     : 79.15% ( 953/1204 )
Functions    : 93.48% ( 86/92 )
Lines        : 88.46% ( 1756/1985 )

Fixed the following bugs:

* UTC timezone wasn't being honored.

* The 4 digit time format (e.g. 1230) wasn't being parsed correctly.

* AM/PM designators weren't being converted to numerical values
  properly.