Implement missing history features

[Jokauppi]

Many user and admin actions were recorded into the database that have not been implemented here like recording product price changes. All of these actions are currently logged, but some of that information may also be needed in the database to implement other features and it should be investigated which action could be required.

This epic can used to track those issues.

• Push action 8 to ITEMHISTORY on buy in #103

[ArktinenKarpalo]

updateProduct updates various data of the product most importantly stock and price which should be recorded to history

[ArktinenKarpalo]

Actually whole itemhistory should be refactored such that there is a dedicated action for each of the following:

1. product purchase
2. product return
3. product buy-in
4. product inventory change

It is very important to get this right for bookkeeping reasons.

[ArktinenKarpalo]

It could be sufficient to log product buy-ins, returns and purchases.
This enables us to a generate report of how many products have disappeared without anybody purchasing them, or if some products were purchased more times than what we had in stock.

Changing product count outside of buy-in/purchase/return is not an issue. Product count is used only during inventories and to predict how much we should buy more, so its not necessary to have any precise history about these changes.