Feature/qr codes with compact share link

[perryholden]

Before testing:

1. I have created CSVs for seeding the data. After running migrations, run the following commands to seed the DB:
   • python3 manage.py seed_setting_setting_string_order
   • python3 manage.py seed_settingoption_abbreviation
2. If new settings are added in the future, you must add values for the following fields in the DB:
   • setting.setting_string_order
   • settingoption.abbreviation

Testing:

1. New links work: http://localhost:8080/settings?settings=BBCAAAACAAAAAAAAAAAAAAAAAAAAA
2. Old links will continue to function
3. If new settings are added in the future, the older abbreviated links will still work but will (obviously) ignore the new settings

Will fail entirely:

1. Correct number of options, but with an invalid option (e.g. "Z" for family-creed): http://localhost:8080/settings?settings=BBCAAAACAAAAAAAAAAAAAAAAAAAAZ
2. Too many items (e.g. one extra, non-existent setting added to the end): http://localhost:8080/settings?settings=BBCAAAACAAAAAAAAAAAAAAAAAAAAAB

Additional notes:

• If there is an error in generating the abbreviated link, it will fall back to default method of generating links.
• If there is an error in decoding the abbreviated link, it will display a warning (see "Will fail entirely" above for examples).
• If there are other values encoded in the URL, the values in the abbreviated 'settings' URL parameter will take precedence.
  • e.g. http://localhost:8080/settings?settings=BBCAAAACAAAAAAAAAAAAAAAAAAAAA&language_style=contemporary
  • In this example, the abbreviated setting will take priority, therefore, the language_style will be set to "traditional"
• If you add collects, these get appended to the settings URL. These "mixed URLs" still work fine, and the QR code is still quite readable:

http://localhost:8080/settings?settings=BAAAAAAAAAAAAAAAAAAAAAAAAAAAA&morning_prayer_collects=3c4e63bf-1324-4d57-aec0-e6d306799a2d,fa685a5f-ed37-4398-b248-7dcd67865abb&midday_prayer_collects=fa685a5f-ed37-4398-b248-7dcd67865abb&evening_prayer_collects=&compline_collects=

Finally, for the position of the QR code on the page, feel free to move it around, restyle it, etc. I am not sure that I like that you have to scroll a bit to see the entire QR code. Also, I did ensure that it works well responsively, but again, feel free to tweak that a bit.

[perryholden]

@blocher - Feel free to suggest feedback and let me know if anything is unclear. Thanks!