Added support for customizing "restrict" configuration options

Previously "restrict" (i.e. "allow connections to ntpd from these addreses") was
hardcoded to '127.0.0.1' and '::1' under the assumption that all nodes using
this module were ntp clients. Added support for customizing the restrict lines
in preparation of ntpd server support. This change will not affect any existing
client configurations.

Signed-off-by: Samuli Seppänen <samuli@openvpn.net>
Updated LICENSE year

Signed-off-by: Samuli Seppänen <samuli@openvpn.net>
Added support for configuring peers and turning on orphan mode

Signed-off-by: Samuli Seppänen <samuli@openvpn.net>
Added Puppet warning header to ntp.conf.erb and ntp.monit.erb

Signed-off-by: Samuli Seppänen <samuli.seppanen@gmail.com>