Update travis.yml to test against less ancient versions of Go. Add badge.

.travis.yml

@@ -1,4 +1,14 @@
+language: go
 script: make release-all
 install: true
 go: 
-- 1.1
+    - 1.1
+    - 1.2
+    - 1.3
+    - 1.4
+    - 1.5
+    - tip
+
+matrix:
+    allow_failures:
+        - go: tip

README.md

@@ -1,3 +1,6 @@
+[![Build
+status](https://travis-ci.org/inconshreveable/ngrok.svg)](https://travis-ci.org/inconshreveable/ngrok)
+
 # ngrok - Introspected tunnels to localhost ([homepage](https://ngrok.com))
 ### "I want to securely expose a web server to the internet and capture all traffic for detailed inspection and replay"
 ![](https://ngrok.com/static/img/overview.png)