Added gemspec.

grack.gemspec

@@ -0,0 +1,17 @@
+Gem::Specification.new do |s|
+  s.name = 'grack'
+  s.version = '0.1.0'
+  s.date = '2013-06-02'
+  s.summary = "This project aims to replace the builtin git-http-backend CGI handler
+distributed with C Git with a Rack application."
+  s.description = "This project aims to replace the builtin git-http-backend CGI handler
+distributed with C Git with a Rack application. By default, Grack uses calls to git on the system to implement Smart-Http. Since the git-http-backend is really just a simple wrapper for the upload-pack
+and receive-pack processes with the '--stateless-rpc' option, this does not actually re-implement very much. However, it is possible to use a different backend by specifying a different Adapter."
+  s.authors = ['Scott Chacon', 'Dawa Ometto']
+  s.email = 'schacon@gmail.com'
+  s.files = ["lib/*", "README.md", "install.txt", "Gemfile"]
+  s.homepage = "http://github.com/schacon/grack"
+  s.license = 'MIT'
+
+  s.add_dependency('rack', '~> 0.9.2.2')
+end