Ability to specify a list of proxies to choose from, always using the first one by default, See wiki (#591)

changedetectionio/model/App.py

@@ -23,7 +23,8 @@ class model(dict):
                 'requests': {
                     'timeout': 15,  # Default 15 seconds
                     'time_between_check': {'weeks': None, 'days': None, 'hours': 3, 'minutes': None, 'seconds': None},
-                    'workers': 10  # Number of threads, lower is better for slow connections
+                    'workers': 10,  # Number of threads, lower is better for slow connections
+                    'proxy': None # Preferred proxy connection
                 },
                 'application': {
                     'password': False,

changedetectionio/model/Watch.py

@@ -39,6 +39,7 @@ class model(dict):
             'trigger_text': [],  # List of text or regex to wait for until a change is detected
             'fetch_backend': None,
             'extract_title_as_title': False,
+            'proxy': None, # Preferred proxy connection
             # Re #110, so then if this is set to None, we know to use the default value instead
             # Requires setting to None on submit if it's the same as the default
             # Should be all None by default, so we use the system default in this case.