Fix ComboBox & mode description for image fill mode
Summary:
BUG: 390571
Reworked ConfigGeneral.qml to properly display ComboBox for image
fill modes, along with descriptive message explaining fill mode.
Changed default change interval (main.xml) to 10.0 instead of the
random-appearing 6.8 original.
(Minor) Capitalized "Frame" in plasmoid title as "Media Frame"
Reviewers: Plasma, mart, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: ngraham, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D10618