MINOR: proxy/listener: support for additional PAUSED state

This patch is a prerequisite for #1626.
Adding PAUSED state to the list of available proxy states.
The flag is set when the proxy is paused at runtime (pause_listener()).
It is cleared when the proxy is resumed (resume_listener()).

It should be backported to 2.6, 2.5 and 2.4
4 files changed