Update font-awesome.min.css to be more CSS compliant

[pablomh]

Hi,

Updating font-awesome.min.css to currently released version (4.6.1 vs 4.3.0 in Flex) has decreased the number of errors using W3C CSS Validator from 18 to 2.

Best regards.
Pablo

[alexandrevicenzi]

Hi @pablomh,

You can send a PR if you want, thanks.

[pablomh]

Done: https://github.com/alexandrevicenzi/Flex/pull/32