[Rails5] Pass more attribute tests for date/time/zones.

[metaskills]

Another chapter in an epic series of getting our custom date time types passing all tests. I feel like we are in a constant battle that has gone downhill since we have to have specific quoting for each datetime type/precision that typically follows %m-%d-%Y format. This has been complicated by the fact that as part of forgetting assignment we could not rely on ActiveModel/Record to pare these strings for us which does not support a) our formats and b) time zones. I am willing to admit that all this work could somehow be easier but I can not see it. Other PRs include:

• [Rails5] Ensure date/time columns are not nil on create/update. Take 2. #528
• Refactor _type_cast & _quote. #534
• [Rails 5] Fix some times coming back nil after save. #537
• Rails5 supports datetime with precision #539

Now that we only have a few dozen tests failing. I might try this freedom patch again to see if things really break dirty support and/or helps reduce the complexity.

• [Rails5] Ensure date/time columns are not nil on create/update. #504

cc @sgrif

[metaskills]

OK, is what it is... #504 is no help in reducing complexity. I think it is all normal for us or my lack to find the simple path.