Merge pull request #73 from flavio-fernandes/fix.validate_feed_key

validate feed keys used needs to allow periods

adafruit_io/adafruit_io.py

@@ -40,9 +40,11 @@ def validate_feed_key(feed_key):
     """
     if len(feed_key) > 128:  # validate feed key length
         raise ValueError("Feed key must be less than 128 characters.")
-    if not bool(re.match("^[a-z0-9-]+$", feed_key)):  # validate key naming scheme
+    if not bool(
+        re.match(r"^[a-z0-9-]+(\.[a-z0-9-]+)?$", feed_key)
+    ):  # validate key naming scheme
         raise TypeError(
-            "Feed key must contain lower case English letters, numbers, and dash."
+            "Feed key must contain lower case English letters, numbers, dash, and one period."
         )