Refactor

* Remove PyOpenSSL based wrapper classes
* Remove unused API calls
* Add certificate renewal via X-Renewal-Signature header
* Remove (extended) key usage handling
* Clean up OpenVPN and nginx server setup code
* Use UDP port 51900 for OpenVPN by default
* Add basic auth fallback for iOS in addition to Android
* Reduce complexity

doc/template.ovpn

@@ -1,47 +0,0 @@
-# Copy this file to /etc/certidude/template.ovpn and customize gateway IP addresses
-
-# Run as client
-client # tls-client; pull
-nobind
-
-# OpenVPN gateway(s), uncomment remote-random to load balance
-comp-lzo
-proto udp
-remote 1.2.3.4
-;remote 1.2.3.5
-;remote-random
-
-# Virtual network interface settings
-dev tun
-persist-tun
-
-# Customize crypto settings
-;tls-cipher TLS-DHE-RSA-WITH-AES-256-CBC-SHA384
-;cipher AES-256-CBC
-;auth SHA384
-
-# Check that server presented certificate has TLS Server flag present
-remote-cert-tls server
-
-# X.509 business
-persist-key
-<ca>
-{{ca}}
-</ca>
-<key>
-{{key}}
-</key>
-<cert>
-{{cert}}
-</cert>
-
-# Revocation list
-<crl-verify>
-{{crl}}
-</crl-verify>
-
-# Pre-shared key for extra layer of security
-;<ta>
-;...
-;</ta>
-