Windows clients integration

[fitz123]

Hi there!

I understand that current pull request is ugly, too many changes, but If you accept my concept I can change it, separate and so on.

Basically my improvements are:

1. Security - at the end you have password protected key
2. Copy key on "builders" pc. At least my use case is generate new users and get the keys for further distribution
3. Using *PKCS cannot read: /etc/openvpn/keys/crl.pem: Permission denied (errno=13) #12 format for keys, because is allow end users upload key in Windows keychain

At the end I have fully automated configuration with secured keys.

Take a look at windows installation guide
This is automatically connection during boot time, not required admin access to use, not required password to connect (but cert itself is password protected)

So up to you

[fitz123]

I really don't want to support my own fork, so please say that changes make sense so I can do it properly and make if pass Travis tests

[klen]

Of course, it makes sense, but I need my time to check the PR. I'll try to do as I can.