Micro prefix

[set-soft]

While testinng the code I found that:

https://github.com/SchrodingersGat/KiBoM/blob/06a14866d8166cfa71ae8ac1a48bda0c160fb380/kibom/units.py#L16

Is using: GREEK SMALL LETTER MU U+03BC GREEK SMALL LETTER MU μ

But, at least for me, is more common to use: MICRO SIGN U+00B5 MICRO SIGN µ

So I'm using:

REFIX_MICRO = [u"μ", u"µ", "u", "micro"]

Which looks pretty lame, and I hope the cut & paste worked ;-), but includes both: the micro sign and the greek letter.

[SchrodingersGat]

Character encoding issues are the most infuriating! Can you submit a PR to fix this ? Cheers :)