Respect empty date/time format settings
Refactor API V3 textile specs
Test that API V3 textile detects wrong content type
Stop RACK from parsing requests for API V3

This allows us to handle parsing errors in the API V3.
Textile endpoint renders 400 on invalid content type
Test render plain endpoint for API V3
Implement render plain endpoint for API V3
Test API V3 WP form response on invalid JSON
Respond with a nice 400 if we cannot parse the JSON request
Test fractional hours
Split fractional hours in hours and minutes
Merge pull request #2277 from opf/hotfix/17228_handle_fractional_hours

17228 handle fractional hours
Merge branch 'release/4.0' into dev

Conflicts:
	lib/api/v3/work_packages/work_package_representer.rb
	spec/lib/api/v3/work_packages/work_package_representer_spec.rb
Merge pull request #2275 from opf/fix/17580_500_when_posting_to_textile_with_json

17580 500 when posting to textile with json
Merge pull request #2263 from opf/feature/frontend-reorganisation-complete
Test that WP response contains linked status
Link WP status
Adapt frontend tests to linked status
Process linked status correctly
fix email is sent when normal confirmation icon clicked