Don't print newline on UnixTerminal exit

Other unix readline-using programs (e.g. bash, mysql, psql, bash) don't
appear to do this.

There was some confusion about this on the mailing list (https://groups.google.com/forum/?fromgroups=#!topic/jline-users/kf4Ek77j_iQ%5B1-25-false%5D), and I'm looking to get rid of it to allow turning jline on and off in the context of a command-line app.

Would be happy to add a configuration instead on this PR, or to go ahead and merge this myself - just let me know.