It only detects i18n.t by default

We match based on the tag name now and not on the namespace,
so revert this again so it's consistent with the other packages

So we only need to define it in one place.

Instead of using the namespace which is hardcoded we use the tag name that was
used to register the element (or the "real" tag name in case of a scoped element).

This way if AppShell is regsitered as "dbp-some-app" it can still be overriden by
specifying "dbp-some-app" in the overrides object.

Upload was broken without any error with webdav-client 4.x. This was
hiding the error.

This option doesn't exist in webdav.client 3.x but is required in 4.x
due to https://github.com/perry-mitchell/webdav-client/issues/266

This will switching between versions easier.

These are all transitive dependencies (or unused) so they get pulled in
anyway.

This reverts commit 421d92f3.

We use i18n.languages in the app-shell to see which languages are available
but this only contains a list of languages it will search in (means, currently
set language, default one and all fallbacks).

We can just set all languages we know as last fallback, so i18n.languages
always contains all languages.

A bit hacky...