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'

gallery_dl/cache.py

@@ -213,6 +213,6 @@ memcache = build_cache_decorator(MEMCACHE)
 try:
     DBCACHE = DatabaseCache()
     cache = build_cache_decorator(MEMCACHE, DBCACHE)
-except RuntimeError():
+except (RuntimeError, sqlite3.OperationalError):
     DBCACHE = None
     cache = memcache