Add tox and testr config and fix apt_pkg error exposed by tox unit_test run

tox.ini

@@ -0,0 +1,29 @@
+[tox]
+envlist = pep8,py27
+skipsdist = True
+
+[testenv]
+setenv = VIRTUAL_ENV={envdir}
+         PYTHONHASHSEED=0
+install_command =
+  pip install --allow-unverified python-apt {opts} {packages}
+commands = ostestr {posargs}
+
+[testenv:py27]
+basepython = python2.7
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
+[testenv:pep8]
+basepython = python2.7
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+commands = flake8 {posargs} hooks unit_tests tests actions
+           charm-proof
+
+[testenv:venv]
+commands = {posargs}
+
+[flake8]
+ignore = E402,E226
+exclude = hooks/charmhelpers