Pin virtualenv version for Python 3.2 support

.travis.yml

@@ -2,7 +2,7 @@ language: python
 python: "3.5"
 install:
   # continue to support Python 3.2 (see issue #84)
-  - pip install pip==7.1.2
+  - pip install "virtualenv<14.0.0"
   - pip install coveralls tox
 script:
   - tox

tox.ini

@@ -9,11 +9,11 @@ commands =
     coverage run setup.py test
     sh -c 'coveralls | true'
 deps =
-    pip==7.1.2
     coverage==3.7.1
     coveralls
     django17: Django>=1.7,<1.8
     django18: Django>=1.8,<1.9
     django19: Django>=1.9,<1.10
+    virtualenv<14.0.0
 passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
 whitelist_externals = sh