Set hosts files via "Gas Mask"

[alebelcor]

I haven't found a way to automate this so instead I have to do this manually.

* Open "Gas Mask" app
* Edit the `combined` file (e.g. change one of the added files, and revert)
* Save the changes

Otherwise the active /etc/hosts file won't reflect the actual combined hosts file.

[alebelcor]

Solved in 2ec0760

[alebelcor]

I reverted the changes because editing the combined hosts file is still needed.