Linux script to transfer a file to a card10 via BLE

I got tired of going in and out of USB mode to transfer scripts to the card10. I also didn't want to use the more or less reliable serial connection.

This script used bluepy to open a connection and uploads the file using the same mechanism that the apps are using.

Caveats:

• Linux seems to always use the slowest allowed connection speed that the device offers. This severely limits data transmission speeds with the currently released firmware. It specifies a 1 second maximum connection interval, leading to one transaction every 2 seconds. Android apparently does not care about the announced connection interval...
• Needs a pairing with the Linux machine. This can be done following the steps in Documentation/bluetooth/card10.rst.
• Does only work under Linux as bluepy only support Linux.
• Further documentation is missing

I'd like to merge this in it's current state.

Things to improve:

• Abstract a file transfer away into a class.
• Allow transmission of multiple files
• Allow transmission of directories
• Honor the --silent option
• Offer pipenv with the requirements