Improve connect step

[peteruithoven]

We've had a complaint that the WiFi-Box couldn't connect to the Taz 5 3D printer. We might be able to improve our connect process by adding more attempts. We might also want to support more baudrates?

Octoprint & Astroprint for example checks lot's of baudrates (250000, 230400, 115200, 57600, 38400, 19200, 9600). They also try longer, they try to get a temperature 5 times on every baudrate. When they receive it they seem to repeat this for 10 times before they consider it "connected".
https://github.com/AstroPrint/AstroBox/blob/3753fc696de1146547cd7a05dc3ef2a4c2265fd8/src/astroprint/printer/marlin/comm.py#L824

Also relevant is logging the initial serial communication: #20

[olijf]

Seems my prusa i3 marlin printer does support both 250000 and 115200, and work flawlessly on both, so might be worth looking into why astroprint choose to include other baudrates.