report process name and uptime for each connected client
report process name and uptime for each connected client

Summary:
It's helpful to know the set of connected clients, when they
connected, and what their status is. Include pid and command line and
uptime in `watchman debug-status`.

Reviewed By: kmancini

Differential Revision: D37436553

fbshipit-source-id: dc9488dab4a0b2e1fd6860a65d3a73bdd5a1e712

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