Adding blink1 formula

[stigi]

Adding a formula for the blink1 command line tool.

Unfortunately they only have a git repo with a master branch, but no real release system.

[MikeMcQuaid]

Please ask them for a tagged, stable release. Until they do so I'm afraid we'll have to pass on this.

[adamv]

Use block form of cd:

cd 'commandline' do
  system "make"
  bin.install "blink1-tool"
end

[adamv]

If no stable tag is forthcoming, this could be a candidate for homebrew-headonly: https://github.com/Homebrew/homebrew-headonly

Or, since brew install can install from any URL, the upstream project itself could carry a Homebrew formula.

[stigi]

thanks @adamv,

Looks like there's no version progress on their side for now. I'll close this PR and will send one on the headonly tap.