Provide OpenVPN runtime version information to plug-ins

Provide OpenVPN runtime version information to plug-ins

Also updated the log_v3 sample-plugin to demonstrate how this
works.

  $ openvpn --plugin log_v3.so --dev tun
  Fri Jul 10 15:17:28 2015 OpenVPN 2.3_git
[git:dev/plugin-version/f05d8623a29078bf+].....
  ...more.openvpn.logging...
  log_v3: OpenVPN 2.3_git  (Major: 2, Minor: 3, Patch:
git:dev/plugin-version/f05d8623a29078bf+)
  ...more.openvpn.logging...
  $

Signed-off-by: David Sommerseth <davids@redhat.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1436534548-21507-3-git-send-email-openvpn.list@topphemmelig.net>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9904
Signed-off-by: Gert Doering <gert@greenie.muc.de>