Message "shutting down server" is displayed only after connections terminated

[sgornick]

Brief Description: When shutting down the server manually from the Client, there is no feedback on the server that it is being shut down until connections are first terminated.

This means someone else looking only at the server might not know it is being shut down and might think it has frozen -- and is not receiving connections.

Operating System (OS and version): OpenBazaar version: 1.1.5

Reproducible Always

Steps to reproduce:

1. On the Client, under Settings -> Advanced click Shut Down the Server.

Observed Behavior: It takes quite some time and reports many "[ConnHandler] [INFO] connection with ..... terminated" messages, and then eventually it will log "[OpenBazaard] [INFO] shutting down server".

Expected Behavior: if instead I click Control-C from the console, I get that "shutting down server" INFO log message immediately. I would expect a shutdown from the client would provide the same instant feedback.