cs-psutils 20170908

Assorted process management functions.

• stop: stop a process with a signal (SIGTERM), await its demise.

• write_pidfile: save a process pid to a file

• remove_pidfile: truncate and remove a pid file

• PidFileManager: context manager for a pid file

• run: run a command and optionally trace its dispatch.

• pipefrom: dispatch a command with standard output connected to a pipe

• pipeto: dispatch a command with standard input connected to a pipe