Add E292 (eof should end with newline) with tests.

test/test_pep8.py

@@ -0,0 +1,20 @@
+import parso
+
+
+def issues(code):
+    module = parso.parse(code)
+    return module._get_normalizer_issues()
+
+
+def test_eof_newline():
+    def assert_issue(code):
+        found = issues(code)
+        assert len(found) == 1
+        issue, = found
+        assert issue.code == 292
+
+    assert not issues('asdf = 1\n')
+    assert_issue('asdf = 1')
+    assert_issue('asdf = 1\n#')
+    assert_issue('# foobar')
+    assert_issue('')