2018 copyright date update

contrib/src/pjproject/pj_uwp_gnutls.patch

contrib/src/pjproject/rfc6062.patch

src/account.cpp

src/account.h

src/account_factory.cpp

src/account_factory.h

src/account_schema.h

src/archiver.cpp

src/archiver.h

src/array_size.h

src/base64.cpp

src/base64.h

src/buildinfo.cpp

src/call.cpp

src/call.h

src/call_factory.cpp

src/call_factory.h

src/channel.h

src/client/callmanager.cpp

src/client/configurationmanager.cpp