* fix(purchasing): more number validation
* test(purchasing): add error cases
Also refactor NaN check and create client mixin
* fix(purchasing): cover "purchase" cases
* WIP(analytics): add / improve tracking
* fix(groups): revert attempt at tracking on group model
* fix(analytics): track questing based on user data
* each buy-operation now has a getItemType method - typo getItemKey - removed unneeded overrides