[COOK-3878] Allow customized data bag search term for adding vpn users
cherrypicking already suggested pr from https://github.com/jhtran/openvpn/commit/33d6a44485552bc9e1d40558da2956ae1ef89958
Merge branch 'master' of https://github.com/howaboutwe/openvpn into howaboutwe

Conflicts:
	attributes/default.rb
	templates/default/server.conf.erb

Re-position node attribute from 50ae9eab6b4a851ea25c36d78ebe733609971cec.