Mention specific versions for circleci

circle.yml

@@ -11,4 +11,4 @@ dependencies:
 
 test:
   override:
-    - tox
+    - tox -e circleci_27 circleci_34 circleci_35 circleci_pypy

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 skipsdist = true
-envlist = py{26,27,34,35,py}
+envlist = py{27,33,34,35,py}
 
 [testenv]
 deps = pytest
@@ -10,3 +10,15 @@ passenv = PYTEST_STATUS_PORT
 
 commands = pip install .
         py.test -v
+
+[testenv:circleci_27]
+basepython = python-2.7.10
+
+[testenv:circleci_34]
+basepython = python-3.4.3
+
+[testenv:circleci_35]
+basepython = python-3.5
+
+[testenv:circleci_pypy]
+basepython = pypy-2.5.0