Change ResponseTimeMiddleware to publish metrics using DjangoMetric
Merge branch 'feature/issue-753-conversation-and-campaign-metrics' into feature/issue-756-use-new-metric-infrastructure-for-metric-publishing
Merge branch 'develop' into feature/issue-756-use-new-metric-infrastructure-for-metric-publishing
Add waffle.io badge (@jerith).
Replace GoWorkerTestMixin.poll_metrics() with get_published_metrics() (Necessary for the new oneshot approach)
Change GoWorkerMixin to use the new metric infrastructure for metric publishing (required a temporary workaround for conversation metric publishing which will go away with #750)
Fix app worker tests after the needed GoWorkerTestMixin changes
Add comment explaining the AttributeError exception handling for ResponseTimeMiddleware
Protect against DNSLookupError in message push.
Protect against replies to messages that don't have conversation keys in reply PUT.
Add test for message without conversation key.
Remove stray debug print.
Add test for DNSLookupError.
Use get_user_model() instead of referencing the User class directly.
Fix call to _patch_http_request_full in event timeout test.
Add test for inbound event pushes that show DNSLookupErrors.
Merge pull request #763 from praekelt/feature/issue-763-get-user-model

Use get_user_model() instead of referencing the User model directly
Put start_time access back into is try block for ResponseTimeMiddleware.process_response (doh)
Merge branch 'feature/issue-762-harden-http-api-vumi-app-against-misc-errors' into develop
Merge branch 'feature/issue-761-use-new-metric-infrastructure-for-metric-publishing' into develop