Merge pull request #124: support Travis CI

From: https://github.com/msabramo/pystache/commit/af04165262191ac9c59de4ee44ebd15b59df23a5
Into: travis-ci

Add .travis.yml for Travis CI: http://travis-ci.org/

.travis.yml

+language: python
+
+python:
+  - 2.5
+  - 2.6
+  - 2.7
+  - 3.2
+  - pypy
+
+script:
+  - python setup.py install
+  - pystache-test ext/spec/specs