General guidelines

Follow 12 factor rules during whole development process.
For cycle cron-like tasks which should be run each X minutes/hours do not forget that each app restart (e.g. after deploy) will reset the timer. So it would be safe to, instead of
```
every(4.hours) { Mailer.perform_async }
```
do
```
every(1.day, at: ['00:00', '04:00', '08:00', ..., '20:00']) { Mailer.perform_async }
```
Add new gems in feature branches (or next). Perform big gem updates on next branch.
Mark hackish places in codebase with # HACK tag with obligatory explanation:
```
# HACK: I did because of reasons
x = x + 1 - 1
```

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