Finish Activity after currency choice

Implemented StartActivityForResult so that
when the user picks the currency it gets transferred
to the budgetSEttings activity and current
activity ends.

-implement startActivityForResult
Save the chosen currency in one SharedPreferences

I figured that the sharedPreferences in CurrencyListActivity
were not needed, because the information was anyways sent
back to the BudgetSettingsActivity, and it would be logical
to save the currency values there.

-Save the passed currency values in SharedPreferences in
BudgetSettings Activity