Add wercker.yml and badge to README

README.md

 # GoTTY - Share your terminal as a web application
 
+[![wercker status](https://app.wercker.com/status/03b91f441bebeda34f80e09a9f14126f/s/master "wercker status")](https://app.wercker.com/project/bykey/03b91f441bebeda34f80e09a9f14126f)
+
 GoTTY is a simple command line tool that turns your CLI tools into web applications.
 
 ![Screenshot](https://raw.githubusercontent.com/yudai/gotty/master/screenshot.gif)

wercker.yml

+box: tcnksm/gox
+
+build:
+  steps:
+    - setup-go-workspace
+    - script:
+        name: go get
+        code: |
+          go get github.com/tools/godep
+          godep restore
+    - tcnksm/gox:
+        os: "darwin linux"
+        arch: "amd64"
+    - yudai/targz:
+        input: $WERCKER_OUTPUT_DIR/pkg
+        output: $WERCKER_OUTPUT_DIR/dist
+
+deploy:
+  steps:
+    - tcnksm/ghr:
+        token: $GITHUB_TOKEN
+        input: dist
+        replace: true