Contact's contribution totals/averages shouldn't cover pending contributions

Currently, the total/average contribution amounts on a contact's tab cover pending contributions.

We should make a call whether we should stick to this approach (because we assume pending contributions will come in eventually, and the total/average should be about what a given contact pledged) or whether we should change these numbers to reflect only the contributions which are complete - i.e., only 'hard cash' that we indeed for sure know was contributed by that contact already. If the latter, we need to fix the code.