[dev] Currencies and Taxes

[Duck]

Currencies and Taxes are needed for all financial modules. To avoid 
duplication of code and data, we should move the code in a central place. How 
do you suggest to to do this:

1. Prepare Horde Administration page - get data with horde external api call
2. Delegate Merk to handle them - get data with merk external api call
3. Write a separate module

For cleaner code I vote for the separate mini module. In future we can extend 
the module with automatic update of exchange values and so on.

Duck