BeagleBone not detected reliably

[bgigous]

In #218, the issue was resolved by adding a check for /sys/bus/nvmem/devices/0-00501/nvmem. However, on my system running the same kernel version as indicated in the linked issue, the board's nvmem on i2c bus 0 was actually located in the 0-00502 folder.

I suggest using python builtins to find the directory matching pattern 0-0050* instead of checking only 0-00501 or 0-00502.