Adding keybase package

packages/keybase.rb

+require 'package'
+
+class Keybase < Package
+  description 'Keybase is encryption for everyone. Installs keybase cli'
+  homepage 'https://keybase.io'
+  version '1.0.40'
+  source_url 'https://github.com/keybase/client/archive/v1.0.40.tar.gz'
+  source_sha256 '79f11737b3bdc279b34d2b978584b3c12e1c24ccdeb3b86dbf7670aa9c634913'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  depends_on 'go'
+
+  def self.install
+    system "go get github.com/keybase/client/go/keybase"
+    system "go build -o #{CREW_DEST_PREFIX}/bin/keybase -tags production github.com/keybase/client/go/keybase"
+  end
+end