Add testing of opt-in opt-out.

Does this have any un-intended side effects?

Author: arokem

Makefile

@@ -0,0 +1,2 @@
+test:
+	py.test --pyargs popylar --cov-report term-missing --cov=popylar

popylar/tests/test_popylar.py

@@ -18,3 +18,12 @@ def test_track_event_with_version():
                             'test_track_event_with_version',
                             software_version=VERSION)
     assert r.status_code == 200, "response is not OK"
+
+
+def test_opt():
+    popylar.opt_out()
+    parser = popylar.get_or_create_config()
+    assert parser['user']['track'] == "False"
+    popylar.opt_in()
+    parser = popylar.get_or_create_config()
+    assert parser['user']['track'] == "True"