Added exception to BudgetItem constructor and Overview now takes in a Budget

BudgetItem now throws exception if BudgetItem budgetAmount is less than zero. Added a Budget object to Overview

added Backend label

requested review from @harrylx

assigned to @andreksv

changed title from Added exception to BudgetItem constructor to Added exception to BudgetItem constructor and Overview now takes in a Budget

changed the description

added 9 commits

• 274e7624...8dc645d6 - 8 commits from branch master
• ecab207d - Merge branch 'master' into 'FileHandlingAndreas'

Compare with previous version

approved this merge request

mentioned in commit bb30da12

merged