certificate: Begin to support remote certificates

src/account.cpp

src/account.h

src/certificate.cpp

src/certificate.h

src/certificatemodel.cpp

src/certificatemodel.h

src/daemoncertificatecollection.cpp

src/daemoncertificatecollection.h

src/private/account_p.h

src/private/certificatemodel_p.h

src/qtwrapper/configurationmanager_wrap.h