merged branch lsmith77/travis-ci (PR #2693)

Commits
-------

0e51e32 point the status icon to 2.0
9d2bd1c tweaked travis configuration
f68c028 [CI] travis-ci.org integration

Discussion
----------

Add travis ci to 2.0

The original PR was send to master and not 2.0, so I cherry picked the two relevant commits.
Once this PR is merged, I will send another PR to master to set the status icon branch accordingly.

.travis.yml

@@ -0,0 +1,7 @@
+language: php
+
+php:
+  - 5.3
+  - 5.4
+
+before_script: php vendors.php

README.md

@@ -1,6 +1,8 @@
 README
 ======
 
+[![Build Status](https://secure.travis-ci.org/symfony/symfony.png?branch=2.0)](http://travis-ci.org/symfony/symfony)
+
 What is Symfony2?
 -----------------