Sahara: add API tests for job binaries

* create/list/get/delete API tests for job binaries in Swift
  and in Sahara database were added
* "test_job_binary_get_data" test was added

Partially implements: blueprint savanna-api-tests

Change-Id: I0f2fcb79b469ad291fb0d9d3acba2fbfbfd7da27
Merge "Sahara: add API tests for job binaries"