Fix incorrect Funds needed calculations
Fix incorrect Funds needed calculations

Change Organisation.euro_funds_needed() and
Organisation.dollar_funds_needed() from using the ORM aggregate() to use
values_list in combination with python sum() to calculate the total funds
needed by projects associated with a given organisation

[Fix #58]

akvo/akvo-rsr,akvo/akvo-rsr,akvo/akvo-rsr,akvo/akvo-rsr