Added add_emitter method

A single emitter no longer needs to be wrapped in an array

Author: fblundun

snowplow_tracker/test/unit/test_tracker.py

@@ -54,3 +54,10 @@ def test_set_timestamp_1(self):
     def test_set_timestamp_2(self):
         dtm = Tracker.get_timestamp(1399021242240.0303)
         self.assertEquals(dtm, 1399021242240)
+
+    def test_add_emitter(self):
+        e1 = Emitter("d3rkrsqld9gmqf.cloudfront.net", method="get")
+        e2 = Emitter("d3rkrsqld9gmqf.cloudfront.net", method="post")
+        t = Tracker(e1, namespace="cloudfront", encode_base64= False, app_id="AF003")
+        t.add_emitter(e2)
+        self.assertEquals(t.emitters, [e1, e2])

snowplow_tracker/tracker.py

@@ -59,7 +59,7 @@ def __init__(self, emitters, subject=None,
                  namespace=None, app_id=None, encode_base64=DEFAULT_ENCODE_BASE64):
         """
             :param emitters:         Emitters to which events will be sent
-            :type  emitters:         list[>0](emitter)
+            :type  emitters:         list[>0](emitter) | emitter
             :param subject:          Subject to be tracked
             :type  subject:          subject | None
             :param namespace:        Identifier for the Tracker instance
@@ -72,7 +72,11 @@ def __init__(self, emitters, subject=None,
         if subject is None:
             subject = _subject.Subject()
 
-        self.emitters = emitters
+        if type(emitters) is list:
+            self.emitters = emitters
+        else:
+            self.emitters = [emitters]
+        
         self.subject = subject
         self.encode_base64 = encode_base64
 
@@ -376,3 +380,15 @@ def set_subject(self, subject):
         """
         self.subject = subject
         return self
+
+    @contract
+    def add_emitter(self, emitter):
+        """
+            Add a new emitter to which events should be passed
+
+            :param emitter: New emitter
+            :type  emitter: emitter
+            :rtype:         tracker
+        """
+        self.emitters.append(emitter)
+        return self