Add instructions to comment out unused gems

Fixes #1398 [ci skip]
Add Russian locale for version 2.3

Add missing translation to en.yml
refactor due date tag on todo for mobile and non-mobile view
fix test regression
use helper class for both due date and show from date
rename module to reflect its generic use
add basic tests for date label helper
update gems and fix test regressions
fix #1712. Number of occurrences was not handled correctly
Fix #1059. make check on new context case insensitive

entering "home" with existing context "Home" will not show a confirmation dialog 
anymore.
update gems and fix failing test

I don't know why the i18n setup code was in there, but it seems to do nothing important
Merge pull request #1710 from AlexStein/russian_t10n

Add Russian locale for version 2.3
update tolk and update nl locale

tolk generated all the other locales too, but no changes to the content were made
update changelog
Remove duplicate changelog note

[ci skip]
put the javascript to handle marking todos complete in its own object with unique name

this should prevent concurrent running ajax calls to mess up the ui
move js genreated for ajax calls into their own object to prevent name clashes

I only modified the js that is most likely to be used in cocurrent calls. This because we
start the development of Tracks 3 that will change all js.
fix regression and refactor todos/update.js a bit
small refactorings of generated javascripts
update gems and nl locale