Extract cost attribute extraction
Activate backlogs attributes in WP overview
Add spent hours to API v3
Add cost object reference to API v3
Use method to initialize helper only ones
Add overall costs information
Remove superfluous includes
Add cost object model spec
Add cost object representer spec
Add work package representer spec
Test summarized cost entries
Add summarized cost entries
Add plug-in's public folder to core's
Add directive for summarized cost entries
Register hook for 'spentUnits' formatting
Load OP Costs JS files into WP view
Introduce SASS styling
Allow to apply styles to WP overview
Correct removal of 'spentTime' attribute
Handle empty list of cost types correctly

Returning 'undefined' will cause the the core to show an empty work
package property.