Bump version to 1.0.0a3 to match tag

sigmavirus24 · sigmavirus24 · commit 169602553905 · 2016-02-11T09:36:06.000-06:00
diff --git a/github3/__about__.py b/github3/__about__.py
@@ -5,7 +5,7 @@
 __author_email__ = 'graffatcolmingov@gmail.com'
 __license__ = 'Modified BSD'
 __copyright__ = 'Copyright 2012-2015 Ian Cordasco'
-__version__ = '1.0.0a2'
+__version__ = '1.0.0a3'
 __version_info__ = tuple(int(i) for i in __version__.split('.') if i.isdigit())
 __url__ = 'https://github3py.readthedocs.org'
 
diff --git a/tox.ini b/tox.ini
@@ -37,12 +37,14 @@ deps =
 commands = flake8 {posargs} github3/ tests/unit/ tests/integration/
 
 [testenv:release]
+usedevelop = false
+skipdist = true
 deps =
-    twine >= 1.4.0
+    twine >= 1.5.0
     wheel
 commands =
     python setup.py sdist bdist_wheel
-    twine upload {posargs} dist/*
+    twine upload {posargs:--skip-existing} dist/*
 
 [testenv:docs]
 deps =
