Add gifgen formula

gifgen.rb

@@ -0,0 +1,13 @@
+class Gifgen < Formula
+  desc "Simple high quality GIF encoding"
+  homepage "https://github.com/lukechilds/gifgen"
+  url "https://github.com/lukechilds/gifgen/archive/1.0.0.zip"
+  version "1.0.0"
+  sha256 "aa561d12c966b11c7c3e5c0be3ad108420e9e9e36a337aa5d08c72a665e74574"
+
+  depends_on "ffmpeg"
+
+  def install
+    bin.install "gifgen"
+  end 
+end