Allow listing a single module in a top match

This makes the following valid syntax for the top.sls file:

base:
  tommy.example.com:   webserver
  jerry.example.com:   dbserver
  alberon.example.com: mailserver

develop:
  saturn.example.com:  webserver

salt/state.py

@@ -1829,6 +1829,8 @@ class BaseHighState(object):
                 if env != self.opts['environment']:
                     continue
             for match, data in body.items():
+                if isinstance(data, string_types):
+                    data = [data]
                 if self.matcher.confirm_top(
                         match,
                         data,

tests/unit/highstateconf_test.py

@@ -0,0 +1,41 @@
+# Import Salt Testing libs
+from salttesting import TestCase
+from salttesting.helpers import ensure_in_syspath
+
+ensure_in_syspath('../')
+ensure_in_syspath('../../')
+
+# Import Salt libs
+import salt.config
+from salt.state import HighState
+
+
+OPTS = salt.config.minion_config(None, check_dns=False)
+OPTS['id'] = 'match'
+OPTS['file_client'] = 'local'
+OPTS['file_roots'] = dict(base=['/tmp'])
+OPTS['test'] = False
+OPTS['grains'] = salt.loader.grains(OPTS)
+
+
+class HighStateTestCase(TestCase):
+    def setUp(self):
+        self.highstate = HighState(OPTS)
+        self.highstate.push_active()
+
+    def tearDown(self):
+        self.highstate.pop_active()
+
+    def test_top_matches_with_list(self):
+        top = {'env': {'match': ['state1', 'state2'], 'nomatch': ['state3']}}
+        matches = self.highstate.top_matches(top)
+        self.assertEqual(matches, {'env': ['state1', 'state2']})
+
+    def test_top_matches_with_string(self):
+        top = {'env': {'match': 'state1', 'nomatch': 'state2'}}
+        matches = self.highstate.top_matches(top)
+        self.assertEqual(matches, {'env': ['state1']})
+
+if __name__ == '__main__':
+    from integration import run_tests
+    run_tests(HighStateTestCase, needs_daemon=False)