MCO-328 reopen logs on signal

With this pull request we add a new optional method on the Logger api, `reopen`, and hook this into SIGWINCH.

SIGWINCH is a little eccentric, but we have already used USR1 and USR2
This wouldnt work on ruby 2 and newer will it? Not allowed to do blocking operations in signal handlers.  Probably the other signal handlers doesn't work on Ruby 2 either but worth keeping in mind for new code?