Ensure SparkRateLimitError.retry_after is a non-negative int

Fix bug number 2 associated with issue #52 :

Ensure that the SparkRateLimitError.retry_after attribute is always a non-negative int, and then (in the automated rate-limit handling code in restsession.py) don't test for the validitiy of the retry_after attribute - make sure it is good and then use it.

Author: cmlccie

ciscosparkapi/exceptions.py

@@ -145,10 +145,10 @@ def __init__(self, response):
         super(SparkRateLimitError, self).__init__(response)
 
         # Extended exception data attributes
-        self.retry_after = int(response.headers.get('Retry-After', 200))
+        self.retry_after = abs(int(response.headers.get('Retry-After', 15)))
         """The `Retry-After` time period (in seconds) provided by Cisco Spark.
 
-        Defaults to 200 seconds if the response `Retry-After` header isn't
+        Defaults to 15 seconds if the response `Retry-After` header isn't
         present in the response headers.
 
         """
@@ -159,10 +159,10 @@ class SparkRateLimitWarning(UserWarning):
 
     def __init__(self, response):
         super(SparkRateLimitWarning, self).__init__()
-        self.retry_after = int(response.headers.get('Retry-After', 200))
+        self.retry_after = abs(int(response.headers.get('Retry-After', 15)))
         """The `Retry-After` time period (in seconds) provided by Cisco Spark.
 
-        Defaults to 200 seconds if the response `Retry-After` header isn't
+        Defaults to 15 seconds if the response `Retry-After` header isn't
         present in the response headers.
 
         """

ciscosparkapi/restsession.py

@@ -277,7 +277,7 @@ def request(self, method, url, erc, **kwargs):
             except SparkRateLimitError as e:
                 # Catch rate-limit errors
                 # Wait and retry if automatic rate-limit handling is enabled
-                if self.wait_on_rate_limit and e.retry_after:
+                if self.wait_on_rate_limit:
                     warnings.warn(SparkRateLimitWarning(response))
                     time.sleep(e.retry_after)
                     continue