Try to remove use of virtualenv in .travis.yml; all the travis builds were...

Try to remove use of virtualenv in .travis.yml; all the travis builds were running under Python 2.7.3 because of it.

.travis.yml

@@ -8,10 +8,8 @@ python:
     - 3.4
     - pypy
 install:
-    - virtualenv env
-    - env/bin/pip install -U setuptools distribute
-    - env/bin/python bootstrap.py
-    - env/bin/python --version
+    - pip install -U setuptools distribute
+    - python bootstrap.py
     - bin/buildout
 script:
     - bin/test -v1 -j99