CC-5697: Editing a linked show's repeat day sets wrong day for show content

Optimized how we store the instance ids that already exist
CC-5697: Editing a linked show's repeat day sets wrong day for show content

Fixed a problem where we can't store the original cc_show_day data
because none can exist at some points. If the user changes the only
repeat day, the cc_show_day rule is deleted first then recreated
CC-5696: Two shows or even three shows playing at once. Unstopable even after reboot

The problem was that we weren't updating the first show's start time if deleting
a repeat show day changes it. This affected the difference between the original
show start time and the new one.
CC-5716: Write database test to check the show content after editing a repeating show and removing a repeat day
Temporarily commenting out test
CC-5716: Write database test to check the show content after editing a repeating show and removing a repeat day
CC-5715: Write database test to check the schedule start times after editing a repeating show and changing the repeat day
CC-5696: Two shows or even three shows playing at once. Unstopable even after reboot
CC-5719: Incorrect show content start time

The show content was getting recalculated twice sometimes.
So if the difference between the original and now show start
date-time and was 2 hours, the scheduled content would have
a difference of 4 hours
CC-5718: Show content can get scheduled in instances that are in the past

Disabled scheduled content into instances that have already played out
Removed setting the show's start date to the first repeating instance's start date
because we already fixed that in CC-5697
CC-5724: Changing start date of a repeating show will update content incorrectly
Broke unit test for adding content to single show
CC-5725: Changing a show's repeat type removes first instance from repeating series
CC-5725: Changing a show's repeat type removes first instance from repeating series
CC-5725: Changing a show's repeat type removes first instance from repeating series
CC-5725 Changing a show's repeat type removes first instance from repeating seriesCC-5726: Write database test cases for CC-5725
Fixed broken test
Fixed changing the start date on a non-repeating show
CC-5727 : History search range using incorrect timezone offset
Merge branch '2.5.x' of github.com:sourcefabric/Airtime into 2.5.x