network: use hostname instead of IP address

[giuseppe-steduto]

After solving #51, we would probably need a way to pass the IP address of the server to the Client and Server classes. However, it would be cool if instead of passing the IP, we could pass a custom domain name (such as myshelfie.gc7.polimi.it).

Notes:

• We could probably exploit the DNS capabilities of a local network to do this and handle the whole logic from a network administration point of view.
• If not possible, we could otherwise program a very basic domain name translation service inside our code (I'd prefer to avoid this)
• I remember someone on Slack asking something related to a library to do something similar... maybe it's worth having a look at it!

[giuseppe-steduto]

It is completely doable with just a bit of network administratrion! Adding a DNS entry for the server IP on the DNS server used by the clients and publishing that IP from server is enough to allow clients to connect to the hostname.