Attempt to debug SSL cert validation error

This changeset introduces a few changes:

* Removes UK Notify Logo URL and config
* Removes UK Notify API URL and replaces with Notify.gov
* Improves the error handler for HTTPErrors to provide actual exception and stack trace information

Signed-off-by: Carlo Costino <carlo.costino@gsa.gov>

notifications_python_client/base.py

@@ -2,6 +2,8 @@ import json
 import logging
 import urllib.parse
 
+from os import getenv
+
 import requests
 
 from notifications_python_client import __version__
@@ -10,21 +12,22 @@ from notifications_python_client.errors import HTTPError, InvalidResponse
 
 logger = logging.getLogger(__name__)
 
+API_PUBLIC_URL = getenv("API_PUBLIC_URL", "localhost")
 
 class BaseAPIClient:
     """
-    Base class for GOV.UK Notify API client.
+    Base class for Notify.gov API client.
 
     This class is not thread-safe.
     """
 
     def __init__(
-        self, api_key, base_url="https://api.notifications.service.gov.uk", timeout=30
+        self, api_key, base_url=API_PUBLIC_URL, timeout=30
     ):
         """
         Initialise the client
         Error if either of base_url or secret missing
-        :param base_url - base URL of GOV.UK Notify API:
+        :param base_url - base URL of Notify.gov API:
         :param secret - application secret - used to sign the request:
         :param timeout - request timeout on the client
         :return: