SSH plugin:  Added an inactivity timeout to ssh_connect.py.  If the user hasn't connected to anything in 120 seconds it will execute a script that waits for the user to press Ctrl-C to exit (tried to make it "Press enter..." but due to threading that didn't work).  When it executes the timeout.sh script the memory consumption of ssh_connect.py should drop to minimal amount, saving loads of memory if you have a lot of idle terminal sessions that have yet to be connected.  This should address the concerns posed in issue #296 (https://github.com/liftoff/GateOne/issues/296) in regards to having 1600 users with one (yet-to-be-connected/idle) terminal each.