Update index.js to support non-integer min-width and max-width

[axryp]

Expanded code to support non-integer min-width / max-width, e.g. @media (min-width: 61.25em)

[DonGissel]

Please, for the love of god, merge this!

[DonGissel]

@ivankravchenko? Please?

[Tyree]

Is this project dead? Really need this merged or I can't use it. :-/

[Tyree]

@axryp Have you tested this? I tried adding your changes to the index.js file in my node_modules and it still doesn't put the queries in the correct order. If I change the em values to px, it does. Any ideas?
It seems to put all the floating points in order, but it puts integers above. So, I end up with 50em, then 87.5, 78.125, 37.5em. It puts the integer before the floating points.
If I change 50 to 50.01, it goes into the correct place.
Also doesn't play nice if you have a px based query mixed in.