Web: enable fix "Default Pages" relation field on web sites/web sections and enable coding style

See merge request !1363
5 jobs for for_testrunner_2
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

passed ERP5.PerformanceTest-Master

failed ERP5.UnitTest-Master

failed ERP5.UnitTest-Master.Medusa

passed SlapOS.Eggs.UnitTest-Master.Python2