Enable Travis CI

For more information, refer https://github.com/atom/ci.

.travis.yml

@@ -0,0 +1,13 @@
+language: objective-c
+
+notifications:
+  email:
+    on_success: never
+    on_failure: change
+
+script: 'curl -s https://raw.githubusercontent.com/atom/ci/master/build-package.sh | sh'
+
+git:
+  depth: 10
+
+sudo: false

README.md

@@ -1,5 +1,7 @@
 # Notational Velocity for Atom
 
+[![Build Status](https://travis-ci.org/seongjaelee/notational-velocity.svg?branch=master)](https://travis-ci.org/seongjaelee/notational-velocity)
+
 [Notational Velocity][1] is an application that stores and retrieves notes. This Atom package implements the some key features from this amazing app:
 
 - Modeless operation