[Test] Add random write/read errors on azure repository

[dadoonet]

From @dadoonet on February 27, 2015 22:32

As we have in AWS plugin with elastic/elasticsearch-cloud-aws#95, we should add random write and read errors while doing snapshot and restore so we can better handle issues and retry.

Copied from original issue: elastic/elasticsearch-cloud-azure#76

[dadoonet]

Related to #51

[tlrx]

This issue is opened for some time now and has no updates. While we think it's still good to have more testing cases we consider that this is very low priority and we should focus on other issues or add more integration tests. I'm going to close this issue, but feel free to comment and add your opinion.