add build and release tox env

Author: retr0h

Diff for: requirements-test.txt

@@ -2,4 +2,5 @@ flake8
 pytest
 pytest-cov
 pytest-mock
+twine
 yapf==0.21.0

Diff for: tox.ini

@@ -5,6 +5,7 @@ envlist =
     lint
     format-check
     doc
+    py{27,36}-build
 skipsdist = true
 
 [travis]
@@ -22,6 +23,7 @@ deps =
     -rrequirements-test.txt
 commands =
     unit: py.test -vv
+    build: python setup.py sdist bdist_wheel
 
 [testenv:lint]
 commands =
@@ -41,3 +43,7 @@ deps=
     -rrequirements-doc.txt
 commands=
     python setup.py build_sphinx --builder=html
+
+[testenv:release]
+commands=
+    twine upload dist/*