Fixes to datetime and timezone aware inputs

• there are three ways Hot Glue deals with Datetime fields:

• (1) with current users who have timezone method (field or method)

• (2) without current user timezone and no global timezone set for your app

• (3) without current user timezone and global timezone set for your app

• For #1, previously this method returned a time zone offset (integer). After v0.5.18, the preferred return value is a Timezone string, but legacy implementation returning offset values will continue to work.
  Your user objects should have a field called timezone which should be a string.

• Note that daylight savings time is accounted for in this implementation.

• For #2 (your user does not have a timezone field and you have not set the timezone globally), all datetimes will display in UTC timezone.

• For #3 (your user does not have a timezone field but you have set the timezone globally), your datetimes will display in the Rails-specified timezone.

• be sure to configure in config/application.rb this:

config.time_zone = 'Eastern Time (US & Canada)'

This should be your business's default timezone.

(#93)
fixes variables be more clear if they are TimeZone objects (https://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html) or are UTC offset (integers -/+ from UTC)

• fixes spec assertions for DateTime and Time fields
• removes randomness causing race conditions in the datetime object specs
  - fixes issue where setting bootstrap-column-width was not preferred if… (#88)
• fixes flash notice output