Add support for OnlyKey DUO

• USB fix #44
• Preliminary OnlyKey DUO support

• Fix for Windows standalone EXE, now all commands succeed without running as admin
• Better key support including ability to set key labels

onlykey-cli.exe - Stand-alone EXE
SHA256 - 591a3afb5eecbb750e5dc2010eb778e4459d12ff22dc60b72dbce2ce09227ec9

onlykey-cli.exe - Stand-alone EXE
SHA256 - d1c6ac743a2b0199d04882263d4b7a64470b76b0e761dda7893caf3c1088f2c1

onlykey-cli.exe - Stand-alone EXE
SHA256 - d7b5f68d3906b6e4ff74f743c48ae8560a98203b7e0367aec884416e35b966b5

Fix dependency issue with prompt toolkit -

http://python-prompt-toolkit.readthedocs.io/en/stable/

"Notice that this is the prompt_toolkit 2.0 documentation. It is incompatible with the 1.0 branch, but much better in many regards. Please read Upgrading to prompt_toolkit 2.0 for more information."

Whats Working -

• The CLI can be used to interact with OnlyKey to load usernames, passwords, etc.

• There are test scripts located in the /tests folder for loading keys and testing decryption/signing.

• PGPMessage.py located in /tests folder works for decrypting encrypted emails.

Whats Not Working

• PGPMessage signing is only working as proof of concept additional development is needed

• PGPMessage only works with RSA 4096 keys right now, additional development is needed to support ECC and additional RSA key sizes.