The entrypoint script now performs a default configuration when no useful
files are found in /docker-entrypoint.d/
The default configuration serves a welcome page in response to all
requests, using Markdown unless text/html is sent in the Accept header.
This provides a useful 'hello world' experience when running a Unit
container for the first time.
If unitd was started with an explicit path then unitc will use that
binary instead of the default PATH to obtain the default control socket
and log file locations.
Now unitc obtains the path to the unitd binary from information
contained in the unitd: main process. If unitd was started with an
explicit path then that path will be used to obtain the default
control socket, instead of using the unitd binary in $PATH.