Added statsd integration into the API

- new client for statsd, follows conventions used elsewhere for configuration
- client wraps underlying library so we can use a config property to send/not send statsd

Added statsd metrics for:
- count of API successful calls SMS/Email
- count of successful task execution for SMS/Email
- count of errors from Client libraries
- timing of API calls to third party clients
- timing of how long messages live on the SQS queue

app/clients/statsd/statsd_client.py

@@ -0,0 +1,26 @@
+from statsd import StatsClient
+
+
+class StatsdClient(StatsClient):
+    def init_app(self, app, *args, **kwargs):
+        StatsClient.__init__(
+            self,
+            app.config.get('STATSD_HOST'),
+            app.config.get('STATSD_PORT'),
+            prefix=app.config.get('STATSD_PREFIX')
+        )
+        self.active = app.config.get('STATSD_ENABLED')
+
+    def incr(self, stat, count=1, rate=1):
+        if self.active:
+            super(StatsClient, self).incr(stat, count, rate)
+
+    def timing(self, stat, delta, rate=1):
+        if self.active:
+            super(StatsClient, self).timing(stat, delta, rate)
+
+
+    def timing_with_dates(self, stat, start, end, rate=1):
+        if self.active:
+            delta = (start - end).total_seconds() * 1000
+            super(StatsClient, self).timing(stat, delta, rate)