Fix clazy issue "src/serverlistmodel.cpp:48:9: warning: Use an empty QLatin1String instead of an empty QStringLiteral [clazy-empty-qstringliteral]".
Initial work to create a model so that new servers can be added to the list. The model will also check if the server is valid before allowing it to be added. Implements network/neochat#11 ### TODO - [x] Add functionality to cache added servers