Cleaner travis image link

docs/index.md

 <iframe src="http://ghbtns.com/github-btn.html?user=tomchristie&amp;repo=django-rest-framework&amp;type=watch&amp;count=true" allowtransparency="true" frameborder="0" scrolling="0" width="110px" height="20px"></iframe>
-[![Build Status](https://secure.travis-ci.org/tomchristie/django-rest-framework.png?branch=restframework2)][travis]
+[![travis-build-image]][travis]
 
 # Django REST framework
 
@@ -140,6 +140,7 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 [travis]: http://travis-ci.org/tomchristie/django-rest-framework?branch=restframework2
+[travis-build-image]: https://secure.travis-ci.org/tomchristie/django-rest-framework.png?branch=restframework2
 [urlobject]: https://github.com/zacharyvoase/urlobject
 [markdown]: http://pypi.python.org/pypi/Markdown/
 [yaml]: http://pypi.python.org/pypi/PyYAML