Set up tox

Add a tox.ini to at least verify packaging and installation work.

Fix one issue found by flake8.

git_os_job/cmd.py

@@ -46,7 +46,6 @@ def main():
     args = parser.parse_args()
 
     ref = args.ref
-    import os
     try:
         ref_hash = subprocess.check_output(
             ['git', 'show-ref', '-s', ref]

tox.ini

@@ -0,0 +1,15 @@
+[tox]
+envlist = py26,py27,py32,py33,style
+
+[testenv]
+setenv =
+    VIRTUAL_ENV={envdir}
+    LANG=en_US.UTF-8
+    LANGUAGE=en_US:en
+    LC_ALL=C
+
+commands = echo "no tests"
+
+[testenv:style]
+deps = flake8
+commands = flake8 git_os_job setup.py