Added tox configuration

tox.ini

@@ -0,0 +1,28 @@
+[tox]
+envlist = cleanup,py27,py34,{py27,py34}-flake8
+
+usedevelop = True
+
+[testenv]
+basepython = python3.4
+usedevelop=True
+setenv = COVERAGE_FILE = .coverage
+commands = py.test --cov=slack_backup --cov-report=term-missing
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
+[testenv:py27-flake8]
+basepython = python2.7
+deps = flake8
+commands = flake8 {posargs}
+
+[testenv:py34-flake8]
+basepython = python3.4
+deps = flake8
+commands = flake8 {posargs}
+
+[testenv:cleanup]
+setenv =
+COVERAGE_FILE = .coverage
+deps = coverage
+commands = coverage erase