Add transports based on Azure PaaS (#891)

* Add transports based on Azure PaaS

This pull request adds two new transport implementations:

- `azurestoragequeues` is implemented on top of Azure Storage
  Queues [1]. This offers a simple but scalable and low-cost PaaS
  transport for Celery users in Azure. The transport is intended to be
  used in conjunction with the Azure Block Blob Storage backend [2].

- `azureservicebus` is implemented on top of Azure Service Bus [3] and
  offers PaaS support for more demanding Celery workloads in Azure. The
  transport is intended to be used in conjunction with the Azure
  CosmosDB backend [4].

This pull request was created together with @ankurokok, @dkisselev,
@evandropaula, @martinpeck and @michaelperel.

[1] https://azure.microsoft.com/en-us/services/storage/queues/
[2] https://github.com/celery/celery/pull/4685
[3] https://azure.microsoft.com/en-us/services/service-bus/
[4] https://github.com/celery/celery/pull/4720

* Exclude Azure transports from code coverage

There is test coverage for the transports but the tests require Azure
credentials to run (passed via environment variables) so codecov doesn't
exercise them.

* Remove env vars to configure transport

* Remove abbreviations

2 files changed, 28 insertions, 0 deletions

diff --git a/t/integration/tests/test_azureservicebus.py b/t/integration/tests/test_azureservicebus.py
new file mode 100644
index 00000000..98dc7340
--- /dev/null
+++ b/t/integration/tests/test_azureservicebus.py
@@ -0,0 +1,12 @@
+from __future__ import absolute_import, unicode_literals
+
+from t.integration import transport
+
+from case import skip
+
+
+@skip.unless_module('azure.servicebus')
+class test_azureservicebus(transport.TransportCase):
+    transport = 'azureservicebus'
+    prefix = 'azureservicebus'
+    message_size_limit = 32000
diff --git a/t/integration/tests/test_azurestoragequeues.py b/t/integration/tests/test_azurestoragequeues.py
new file mode 100644
index 00000000..eb66c6be
--- /dev/null
+++ b/t/integration/tests/test_azurestoragequeues.py
@@ -0,0 +1,16 @@
+from __future__ import absolute_import, unicode_literals
+
+from t.integration import transport
+
+from case import skip
+
+
+@skip.unless_module('azure.storage.queue')
+class test_azurestoragequeues(transport.TransportCase):
+    transport = 'azurestoragequeues'
+    prefix = 'azurestoragequeues'
+    event_loop_max = 100
+    message_size_limit = 32000
+    reliable_purge = False
+    #: does not guarantee FIFO order, even in simple cases.
+    suppress_disorder_warning = True