[ #11219 ] Change license to LGPLv2 for libraries

src/Account.cpp

src/Account.h

src/AccountList.cpp

src/AccountList.h

src/COPYING

src/Call.cpp

src/Call.h

src/CallModel.cpp

src/CallModel.h

src/CallModel.hpp

src/Contact.cpp

src/Contact.h

src/ContactBackend.cpp

src/ContactBackend.h

src/Item.cpp

src/Item.h

src/callmanager_interface_singleton.cpp

src/callmanager_interface_singleton.h

src/configurationmanager_interface_singleton.cpp

src/configurationmanager_interface_singleton.h