fix some smaller stuff

- remove support for old windows config paths
- catch exception if cache-database can't be opened
- fix username/password settings for unit tests
- rename variable 'max_tries' to 'retries'

test/test_extractors.py

@@ -18,8 +18,8 @@ class TestExtractors(unittest.TestCase):
         name = "gallerydl"
         email = "gallerydl@openaliasbox.org"
         config.set(("cache", "file"), ":memory:")
-        config.set(("username",), name)
-        config.set(("password",), name)
+        config.set(("extractor", "username"), name)
+        config.set(("extractor", "password"), name)
         config.set(("extractor", "nijie", "username"), email)
         config.set(("extractor", "seiga", "username"), email)