Create lib/dates

Several modules were importing datetime format strings from the UDF
module. I wanted to add a helper function that made use of our
"standard" format string but, While not duplicating string literals is
good, entangling unrelated modules is less good.
Fix type error
Log when validation fields don't have Dom elements

There's nothing stopping the server from returning a validation error
that doesn't correspond to a validation field for the client form that issued
the request. This logs cases where that happens so devs can fix them.
Fix literal validation errors
Fix dynamically built up errors

fixes #1653 on github
Merge pull request #1749 from steventlamb/bug/fix_inline_edit_form

Bug/fix inline edit form
Merge pull request #1751 from steventlamb/topic/fix_validation_errors

Topic/fix validation errors
Make randomly failing test less likely to fail

fixes #1746 on github
Merge pull request #1752 from steventlamb/bug/make_randomly_failing_test_less_likely

Make randomly failing test less likely to fail
Add unix timestamp helper

The Stripe APIs use Unix timestamps. This helper wraps up the somewhat
ugly method of creating one in Python.
Merge pull request #1748 from jwalgran/topic/create-lib-stringdate

Create lib/stringdate