The projectteam/costs table is now splitted in two versions

Instead of 'can-see-financials' checks thoughout the table, there are now
simple two separate tables.
Added 'inkomsten' column
Started making the costs/income columns more prominent
Moved 'left to book' badge to pl/pm column: less visual distraction
Removed header (it cluttered too much)
Added 'reservation' attr on Project and removed special 'reservation' budget item.

Including data migration.
Small beautification in log message
Using reservation in templates
Upped cache versions and consolidated on 'cache_version' name
Fix for aggregate returning None
Improved logging
Fixed colspan
Added heading for costs
Added bool for 'is third party cost' for marking BudgetItems
Treating all budget items as costs (instead of as income)
Data migration for swapping sign of budgetitem amounts (it are now costs)
Differentiating between costs and income
Fixed team page
Added optional field to assign budget from one project to another
Added automatic discovery of many from/to budget transfers