MINOR: mworker/cli: add 'debug' to 'show proc'

MINOR: mworker/cli: add 'debug' to 'show proc'

This patch adds a 'debug' parameter to the 'show proc' command of the
master CLI. It allows to show debug details about the processes.

Example:

echo 'show proc debug' | socat /tmp/master.sock -
\#<PID>          <type>          <reloads>       <uptime>        <version>      		<ipc_fd[0]>     <ipc_fd[1]>
391999          master          0 [failed: 0]   0d00h00m02s     3.1-dev10-b9095a-63		5               6
\# workers
392001          worker          0               0d00h00m02s     3.1-dev10-b9095a-63		3               -1
\# programs