Renamed _gas into _network_gas for three converters in buildings sector.
Re-imported all datasets; this includes the changed buildings_final_demand_network_gas_parent_shares.csv.
Renamed buildings_final_demand_for_space_heating parent_share from gas to natural_gas.
Renamed _gas for to _network_gas for example dataset.
.gpg files after importing etdataset.
Merge pull request #865 from quintel/renaming_gas

Renamed _gas into _network_gas for three converters in buildings sector.