Server must be a URL; Request method

Capture device (—server) must be a URL.
Request method allows a different HTTP request in a subclass.
Bug fixes.
Experimental capture device monitor.

Very rough proof of concept code to allow a capture device to be
controlled from the command line or with a Raspberry Pi + Adafruit 2x16
LCD and buttons.
Clarify 'duration'

When creating or extending a capture, duration is measured in seconds.
Code clean-up

An IP address can no longer be specified by itself, It must be a URL.
Exceptions are now in the class, and are translated to status codes and
reason messages.
Documentation is updated and a new 'typical usage' section has been
added.
removed this code for now