fix(Tests): Date() usage failing on Safari 5

Safari is bailing on things like `new Date('2009-12-12'). According to SO it looks its date parsers doesn't like the hashes. This change uses the standard
argument-based method of date creation.

Additionally, Safari 5 appears to offset the timezone inappropriately.
This change also uses .toISOString() for date string comparisons, rather
than using the explicit typed-out date string.