Angular6 upgrade

Hide the wrapper component when there is no text content

Fixed issue where facets could not be changed when you are logged in

Conflicts:
	src/app/core/cache/builders/remote-data-build.service.ts
	src/app/core/metadata/metadata.service.ts
	src/app/core/shared/item.model.ts
	src/app/shared/loading/loading.component.ts
	yarn.lock

Issue 313: add support for paginated properties on dspace objects

Issue 311: No files item page bugfix

#293 Added link with the query quoted for search results if empty

If there is an error 400 or a search returns an empty result this commit will show a link with the query quoted. 
Also improved testing of search results component as the component has changed.

Hide metadata labels without value