Allow testing with tox

.gitignore

@@ -3,6 +3,7 @@ build
 dist
 pygit2.so
 _pygit2.so
+.tox/
 test/*.pyc
 test/__pycache__
 pygit2/*.pyc

setup.py

@@ -108,7 +108,8 @@ class TestCommand(Command):
 
 class sdist_files_from_git(sdist):
     def get_file_list(self):
-        popen = Popen(['git', 'ls-files'], stdout=PIPE, stderr=PIPE)
+        popen = Popen(['git', 'ls-files'], stdout=PIPE, stderr=PIPE,
+                      universal_newlines=True)
         stdoutdata, stderrdata = popen.communicate()
         if popen.returncode != 0:
             print(stderrdata)

tox.ini

@@ -0,0 +1,6 @@
+[tox]
+envlist = py27,py32,py33,py34,py35,pypy,pypy3
+
+[testenv]
+commands =
+    python setup.py test