Check more paths for plugins.

Summary:
Signed-off-by:
check bin/AtCore on (craft on windows but only when packaged)
check ../PlugIns/AtCore (mac os package w/ framework Qt)
These are for clients more then atcore.

Reviewers: Atelier: AtCore, laysrodrigues, tcanabrava

Reviewed By: Atelier: AtCore, laysrodrigues, tcanabrava

Subscribers: tcanabrava, laysrodrigues, Atelier: AtCore

Tags: Atelier: AtCore

Differential Revision: https://phabricator.kde.org/D13632