Update server example

[djui]

Try to keep the server example in sync with the latest implementation.

7ca58a5 started this effort but only for the client example.

[djui]

In general I am a bit worried about the current state of versioning:

• Neither v0.4.4 of the crate work with the example.
• Nor does master work with the example.

The API has changed beyond and requires a new version. The example code works with master.

I would suggest to make the current state of the project obvious in the head of the README.md and additionally clearly state with examples work with the crate version (v0.4.4) and which would work with master.