added tox and basic import test

tests.py

@@ -0,0 +1,8 @@
+import unittest
+
+
+class ShipStationTests(unittest.TestCase):
+
+    def test_shipstation_imports_correctly(self):
+        from shipstation.api import ShipStation
+        ShipStation('123', '456')

tox.ini

@@ -0,0 +1,12 @@
+# Tox (http://tox.testrun.org/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+envlist = py27
+
+[testenv]
+commands = nosetests {posargs}
+deps =
+    nose