Build is missing version information

[micolous]

When you build Proxmark with these Homebrew scripts, it downloads a ZIP file of a tagged release from GitHub:

homebrew-proxmark3/proxmark3.rb

Line 4 in 801cb4a

url "https://github.com/proxmark/proxmark3/archive/v3.1.0.tar.gz"

GitHub does not include any git metadata in these ZIP files, which triggers Proxmark/proxmark3#12.

As a result, anyone flashing firmware built by these Homebrew scripts will have version information that looks like one of the (many) sellers of Proxmark3 hardware which do not comply with the GPL, and makes troubleshooting more difficult.