Use KAboutData to set information about the daemon

Summary:
I noticed this when the daemon crashed and drkonqi refused to submit
a bug report, complaining about a missing bug reporting address.
Additionally, using KAboutData also saves initialising some
properties of QCoreApplication manually.

Test Plan:
sent SIGSEGV to kdeconnect, could've reported the crash
with drkonqi; checked with GammaRay that the properties of
QCoreApplication are initialised.

Reviewers: KDE Connect

Subscribers: kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D18542