Add Bundler patch for retries.

Gemfile

@@ -39,3 +39,62 @@ group :test do
   gem 'rspec', '~> 2.11'
   gem 'sinatra-contrib'
 end
+
+require 'bundler/installer'
+
+module ::Bundler
+  class Installer < Environment
+    MAX_RETRIES = 3
+
+    def install_gem_from_spec(spec, standalone = false)
+      retries = 1
+      # Download the gem to get the spec, because some specs that are returned
+      # by rubygems.org are broken and wrong.
+      Bundler::Fetcher.fetch(spec) if spec.source.is_a?(Bundler::Source::Rubygems)
+
+      # Fetch the build settings, if there are any
+      settings = Bundler.settings["build.#{spec.name}"]
+      Bundler.rubygems.with_build_args [settings] do
+        spec.source.install(spec)
+        Bundler.ui.debug "from #{spec.loaded_from} "
+      end
+
+      # newline comes after installing, some gems say "with native extensions"
+      Bundler.ui.info ""
+      if Bundler.settings[:bin] && standalone
+        generate_standalone_bundler_executable_stubs(spec)
+      elsif Bundler.settings[:bin]
+        generate_bundler_executable_stubs(spec, :force => true)
+      end
+
+      FileUtils.rm_rf(Bundler.tmp)
+    rescue Gem::RemoteFetcher::FetchError => e
+      if retries <= MAX_RETRIES
+        Bundler.ui.warn "#{e.class}: #{e.message}"
+        Bundler.ui.warn "Installing #{spec.name} (#{spec.version}) failed."
+        Bundler.ui.warn "Retrying (#{retries}/#{MAX_RETRIES})"
+        retries += 1
+        sleep retries
+        retry
+      else
+        Bundler.ui.warn "Installing #{spec.name} (#{spec.version}) failed after #{retries} retries: #{e.message}."
+        Bundler.ui.warn "Giving up"
+        msg = "An error, most likely because of network issues, has occurred trying to install #{spec.name} (#{spec.version}), "
+        msg << "and Bundler cannot continue."
+        raise Bundler::InstallError, msg
+      end
+    rescue Exception => e
+      # install hook failed
+      raise e if e.is_a?(Bundler::InstallHookError) || e.is_a?(Bundler::SecurityError)
+
+      # other failure, likely a native extension build failure
+      Bundler.ui.info ""
+      Bundler.ui.warn "#{e.class}: #{e.message}"
+      msg = "An error occurred while installing #{spec.name} (#{spec.version}),"
+      msg << " and Bundler cannot continue.\nMake sure that `gem install"
+      msg << " #{spec.name} -v '#{spec.version}'` succeeds before bundling."
+      Bundler.ui.debug e.backtrace.join("\n")
+      raise Bundler::InstallError, msg
+    end
+  end
+end