(search) Fix searching tags with spaces
Tags containing blank spaces were not handled properly in the search widget.
Now we enclose them in quotes and strip the quotes before setting them to the widget.
No artifacts when searching tags containing spaces
Added test cases to bin/dolphinquerytest
Reviewers: Dolphin, elvisangelaccio, ngraham, meven
Reviewed By: Dolphin, elvisangelaccio, ngraham
Subscribers: meven, kfm-devel
Differential Revision: https://phabricator.kde.org/D26369