Added alternative adafruit_hashlib import and warning message in neither is present

Author: michalpokusa

adafruit_httpserver/response.py

@@ -17,9 +17,19 @@
 import os
 import json
 from binascii import b2a_base64
-import hashlib
 from errno import EAGAIN, ECONNRESET, ETIMEDOUT, ENOTCONN
 
+try:
+    try:
+        import hashlib
+    except ImportError:
+        import adafruit_hashlib as hashlib
+except ImportError:
+    print(
+        "WARNING: hashlib module not available and adafruit_hashlib not installed.",
+        "Websocket support will not work.",
+    )
+
 from .exceptions import (
     BackslashInPathError,
     FileNotExistsError,