Optimisation of metamodel loading + fixed bugs

client/src/app/admin/admin-routing.module.ts

client/src/app/admin/admin.component.ts

...pp/admin/containers/attribute/attribute-list.component.ts

.../app/admin/containers/database/database-list.component.ts

.../app/admin/containers/database/edit-database.component.ts

.../app/admin/containers/dataset/dataset-list.component.html

...rc/app/admin/containers/dataset/dataset-list.component.ts

...rc/app/admin/containers/dataset/edit-dataset.component.ts

...src/app/admin/containers/dataset/new-dataset.component.ts

...nt/src/app/admin/containers/group/edit-group.component.ts

...nt/src/app/admin/containers/group/group-list.component.ts

client/src/app/admin/containers/group/new-group.component.ts

...min/containers/instance/configure-instance.component.html

...admin/containers/instance/configure-instance.component.ts

.../app/admin/containers/instance/edit-instance.component.ts

.../app/admin/containers/instance/instance-list.component.ts

...t/src/app/admin/containers/settings/settings.component.ts

.../src/app/admin/containers/survey/edit-survey.component.ts

...t/src/app/admin/containers/survey/new-survey.component.ts

.../src/app/admin/containers/survey/survey-list.component.ts