First draft at a status page
make it work on older psutils, hopefully :-(
reducing number of process calls

Calling getcwd() or cwd() too soon leads to an error, as it requires you
to have corresponding permissions. Those special contents are not
required for filtering the processes, so they are computed/cached
on-demand.
move to json for app status

This resolves the HTML templating issues pointed out by @esc while
remaining readable, without requiring jinja2.
setting the application/json content type

This makes the page more readable in a browser and is also much more
correct than the default text/html.
adding the yadtreceiver version to the app status
default int values must be strings, actually

The config parser code uses the default value as default return value of
the parser (and will check isdigit() for int values). If the value is
already the desired type, this check will fail (int has no isdigit(),
this is a string method).
making the app status port configurable
handling missing permissions for cwd()

If for some reason there is a command running that does not belong to us
(the yadtreceiver user) then getcwd() will fail with an error. This
patch allows returning a default value if that is the case.
Merge pull request #2 from yadt/feature/app_status

Feature/app status