[timeline] Fix warning, add missing UDS entry for "."

Summary:
kf5.kio.core: UDSEntry for '.' not found, creating a default one. Please
fix the "kio_timeline" KIO slave

Test Plan:

1. point klauncher to fixed ioslave
2. dolphin timeline:/

Reviewers: Baloo, Frameworks, poboiko, ngraham, astippich

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D20100