Need to be more careful to wait for networking to startup

[Techcable]

Immediately after startup, Dis4IRC makes a connection to discord.com.

Using the systemd service file, I very frequently get issues connecting with "name resolution":
https://gist.github.com/Techcable/183d6b3752eb90fe897052a91af21370

We need to inform systemd to wait until networking has been fully setup before starting the service. There should be something about "depends on networking" or something.

On a related issue, Dis4IRC recovers poorly if connection is lost with discord.com