Remove fetch_object monkey-patch to ActiveSupport::Cache

Rails caching now fully supports storing arbitrary ruby objects, so
this patch is no longer necessary.
Removing postgresql quoting monkey-patch

We can't currently run OCW on postgres anyway, and this three-year-old
patch is likely unnecessary.
Remove unnecessary hash_to_xml_workaround

Once upon a time, ActiveSupport didn't support serializing arrays to
XML (what?), so we added this workaround. Now, it works just fine.
[gem] Upgrade the 'color' gem
Remove Object#logit, just use logger.info instead
Remove Time#today monkey-patch