Added embedded activities to the work package resource
Merge branch 'feature/api_work_package_show_experimental' into feature/api_work_package_embedded_activities
Created activity model
Created representer for activities
Fixed paths to modules
Allowed API to render nil for activity's user
Specified host for the test env
Fixed wrong path in application_helper_test.rb
Merge pull request #1528 from opf/feature/api_work_package_embedded_activities

Feature/api work package embedded activities