add a flag to control if DApps can be listed or not

We are publishng to the market all dapps at this moment. It has become our main mode of deployment.

But, for several dapps (glass-wallet, dsu-explorer, etc) we only want them accessible via their ID.

Otherwise when listing dapps in the wallet, they'll also appear which is not desirable.

For that effect add a new publishing flag (this will extend to glass-toolkit) that allows to determine if the dapp we are publishing can or not be listed