Add NoAuthentication and make it the default

[pmeier]

Per title when #178 is done. We have had several reports that the default demo authentication is no intuitive:

• what is default username and password #167
• Method not allowed #156 (reply in thread)
• External contributions accepted? #166 (comment)

We tried to mitigate it somewhat with

• add print for demo auth #157
• document default login credentials #168

but ultimately adding extra documentation doesn't make it any more intuitive.

Since no one needs authentication for local experimentation, we should have a NoAuthentication class that should be the default.

cc @nenb