ci: add job to publish iOS release artifact on merge to master (#565)
ci: add job to publish iOS release artifact on merge to master (#565)

Adds a job that runs on master and builds/uploads a zip artifact of the `Envoy.framework` for iOS using the release configurations. This should make it easier for consumers to utilize the most recent iOS versions of Envoy Mobile.

Resolves https://github.com/lyft/envoy-mobile/issues/547.

Tested against this PR, which resulted in the expected artifacts being uploaded successfully:

<img width="326" alt="Screen Shot 2019-10-30 at 2 15 05 PM" src="https://user-images.githubusercontent.com/2643476/67899621-ebcab880-fb1f-11e9-89f9-25fac9a96097.png">

Signed-off-by: Michael Rebello <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@michaelrebello.com>
envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile