[mod] settings.yml can be /etc/searx/settings.yml

The exact order is
* first from SEARX_SETTINGS_PATH,
* if not found then from searx code base,
* if not found then from /etc/searx/settings.yml
* if not found an exception stops searx loading

searx/__init__.py

 import certifi
 import logging
 from os import environ
-from os.path import realpath, dirname, join, abspath
+from os.path import realpath, dirname, join, abspath, isfile
 from ssl import OPENSSL_VERSION_INFO, OPENSSL_VERSION
 try:
     from yaml import load
 searx_dir = abspath(dirname(__file__))
 engine_dir = dirname(realpath(__file__))
 
-# if possible set path to settings using the
-# enviroment variable SEARX_SETTINGS_PATH
+
+def check_settings_yml(file_name):
+    if isfile(file_name):
+        return file_name
+    else:
+        return None
+
+# find location of settings.yml
 if 'SEARX_SETTINGS_PATH' in environ:
-    settings_path = environ['SEARX_SETTINGS_PATH']
-# otherwise using default path
+    # if possible set path to settings using the
+    # enviroment variable SEARX_SETTINGS_PATH
+    settings_path = check_settings_yml(environ['SEARX_SETTINGS_PATH'])
 else:
-    settings_path = join(searx_dir, 'settings.yml')
+    # if not, get it from searx code base or last solution from /etc/searx
+    settings_path = check_settings_yml(join(searx_dir, 'settings.yml')) or check_settings_yml('/etc/searx/settings.yml')
+
+if not settings_path:
+    raise Exception('settings.yml not found')
 
 # load settings
 with open(settings_path) as settings_yaml:
     logging.basicConfig(level=logging.WARNING)
 
 logger = logging.getLogger('searx')
-
+logger.debug('read configuration from %s', settings_path)
 # Workaround for openssl versions <1.0.2
 # https://github.com/certifi/python-certifi/issues/26
 if OPENSSL_VERSION_INFO[0:3] < (1, 0, 2):

searx/utils.py

     return resources_directory
 
 
-def get_themes(static_path):
+def get_themes(templates_path):
     """Returns available themes list."""
-    themes = os.listdir(os.path.join(static_path, 'themes'))
+    themes = os.listdir(templates_path)
     if '__common__' in themes:
         themes.remove('__common__')
     return themes

searx/webapp.py

 default_theme = settings['ui']['default_theme']
 templates_path = get_resources_directory(searx_dir, 'templates', settings['ui']['templates_path'])
 logger.debug('templates directory is %s', templates_path)
-themes = get_themes(static_path)
+themes = get_themes(templates_path)
 result_templates = get_result_templates(templates_path)
 global_favicons = []
 for indice, theme in enumerate(themes):