feat: User data from file

- added ability to read user data from file (#93, thanks @Negashev)

Author: JonasProgrammer

README.md

@@ -15,8 +15,8 @@ You can find sources and pre-compiled binaries [here](https://github.com/JonasPr
 
 ```bash
 # Download the binary (this example downloads the binary for linux amd64)
-$ wget https://github.com/JonasProgrammer/docker-machine-driver-hetzner/releases/download/3.9.2/docker-machine-driver-hetzner_3.9.2_linux_amd64.tar.gz
-$ tar -xvf docker-machine-driver-hetzner_3.9.2_linux_amd64.tar.gz
+$ wget https://github.com/JonasProgrammer/docker-machine-driver-hetzner/releases/download/3.10.0/docker-machine-driver-hetzner_3.10.0_linux_amd64.tar.gz
+$ tar -xvf docker-machine-driver-hetzner_3.10.0_linux_amd64.tar.gz
 
 # Make it executable and copy the binary in a directory accessible with your $PATH
 $ chmod +x docker-machine-driver-hetzner