fix usages prices forms
fix devices and devices-cores team billing models with ventures subset; team total_cost fixed
fixes from PR comments
Merge pull request #126 from mkurek/fix/services-teams-billing

fix devices and devices-cores team billing models with ventures subset
docstring improved
Merge pull request #125 from mkurek/fix/fix-usages-prices-forms

fix usages prices forms
fixed subset of ventures in team by time billing model
Merge pull request #128 from mkurek/fix/services-teams-billing-by-time

fixed subset of ventures in team by time billing model