generate iOS pem push certificates and pfx package files for node apn library

As a future reference to myself, this is how we transformed iOS pem certificates into PFX packages for use with nodes apn library

1. Use this guide by Ray Wnederlich to create the push certificates
   • create keys through app id preferences screen in https://developer.apple.com interface.
   • export certificate and keys to .p12 from keychain using following commands
     • openssl pkcs12 -in PushProdKeys.p12 -out PushProdKeys.pem -nodes -clcerts
     • openssl pkcs12 -in PushDevKeys.p12 -out PushDevKeys.pem -nodes -clcerts
2. Test the prod certificates with openssl s_client -connect gateway.push.apple.com:2195 -cert PushProd.pem -key PushProdKeys.pem
3. Prepare .pem certificates using the guide at node-apn github
   • openssl x509 -in aps.cer -inform DER -outform PEM -out PushProduction.pem
   • openssl x509 -in aps_development.cer -inform DER -outform PEM -out PushDev.pem
4. Create pfx package by following this guide on stackoverflow
   • openssl pkcs12 -export -out pushprod.pfx -in PushProd.pem -inkey PushProdKeys.pem
   • openssl pkcs12 -export -out pushdev.pfx -in PushDev.pem -inkey PushDevKeys.pem
5. Create base64 pfx package for use in env vars:
   • cat pushprod.pfx | base64 > pushprod.pfx.txt
   • cat pushdev.pfx | base64 > pushdev.pfx.txt