Add a few more CHANGELOG entries for 2.2.0 release
Add spec to ensure distinct product are returned in api
bump friendly_id version to 5.0.3

Fixes #4350
Fix Spree::TaxonsHelper#taxon_preview not to show duplicate products

Fixes #4361
remove adjustments finalize!

According to commit 953c960680f284a2eb97b160a4610a72494ce107.
finalize event has been removed from Spree::Adjustment.
It will throw error in after_ship method since no finalize! method in adjustment now.
```
undefined method `finalize!' for #<Spree::Adjustment:0x000001095a1180>
```
move deliver email under completed_at touch, to avoid email to brake since the completead_at would be nil

Fixes #4363
Use can_supply in stead of deprecated in_stock in frontend

Fixes #4364