Add the ability to refresh access token if refresh token is available in environment variables

.gitignore

@@ -1 +1,2 @@
-.env
+.env
+__pycache__/

client.py

@@ -10,7 +10,7 @@ load_dotenv()
 
 class TradeStationClient:
 
-    def __init__(self) -> None:
+    def __init__(self, refresh_token: str = None) -> None:
         self.id = getenv('TRADESTATION_CLIENT_ID')
         self.redirect_uri = getenv('TRADESTATION_REDIRECT_URI')
         self.scope = getenv('TRADESTATION_CLIENT_SCOPE')
@@ -23,6 +23,11 @@ class TradeStationClient:
         self.id_token = None
         self.refresh_token = None
 
+        # For bypassing normal authorization flow.
+        if refresh_token:
+            self.refresh_token = refresh_token
+            self.refresh_access_token()
+
     def open_authorization_url(self):
         """
         Open the TradeStation authorization URL in the default web browser.