Added PyPy 3 to tox.ini.

tox.ini

@@ -4,6 +4,7 @@ envlist =
     3.3,
     3.4,
     pypy
+    pypy3
 
 [testenv]
 sitepackages = False
@@ -49,6 +50,17 @@ setenv = C_DEBUG_TEST = 1
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
            pip install -U -r{toxinidir}/requirements/dev.txt
            nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           
+[testenv:pypy3]
+basepython = pypy3
+deps = -r{toxinidir}/requirements/default.txt
+-r{toxinidir}/requirements/test.txt
+-r{toxinidir}/requirements/test-ci.txt
+-r{toxinidir}/requirements/dev.txt
+setenv = C_DEBUG_TEST = 1
+commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
+pip install -U -r{toxinidir}/requirements/dev.txt
+nosetests -xsv --with-coverage --cover-inclusive --cover-erase []         
 
 [testenv:docs]
 deps = -r{toxinidir}/requirements/docs.txt