getclient: Use openssl to prune comments

* The EasyRSA tools create a certificate file with all the metadata
  readable.  This makes the config file larger then it needs to be, so
  prune it.
* Retrieve text files with `openssl x509 -in <crt> -noout -text`

bin/ovpn_getclient

@@ -45,7 +45,7 @@ remote $OVPN_CN $OVPN_PORT $OVPN_PROTO
 $(cat $EASYRSA_PKI/private/${cn}.key)
 </key>
 <cert>
-$(cat $EASYRSA_PKI/issued/${cn}.crt)
+$(openssl x509 -in $EASYRSA_PKI/issued/${cn}.crt)
 </cert>
 <ca>
 $(cat $EASYRSA_PKI/ca.crt)