Add an hdfs data source example to the rest doc

Change-Id: I83ea70213f6f1a771fa97662ebd73421ddbdedb6
Add a config flag to disable cluster deletion after integration test

Node-side failures are not always clear in the integration test logs.
Examination of the cluster can be helpful in understanding these failures.
Allow cluster deletion to be disabled after integration tests.  This is
meant for use when running "tox -e integration" on a local host.

Closes-Bug: #1271981

Change-Id: I03e0df3e72178bdef5c5749f7557a23da3994335
Fixed potential problems in test_periodic.py

* Added check on get_job_status.call_count in test_job_status_update.
  Without such check test checks nothing (test passes after replacing
  datetime.datetime.now() with None for the first excecution)

* Added return of global config in test_cluster_terminate (to avoid
  problems like we faced with test_topology)

* Changed check of called arguments in test_cluster_terminate to supported
  method. Check using mock internals is not a good idea

Change-Id: I249efe5e66a7658f73b1e9455eaa3e0683ef043f
Require "libs" for MapReduce and Java jobs and disallow "mains"

The validation for MapReduce and Java job types was too loose.
It required that mains or libs be set, but in reality libs is
required and mains is useless in Oozie workflows for these types.

Partial-Bug: #1272506

Change-Id: I94a86f9581346741f935e2b79b3ba582b06f1f76
Updated from global requirements

Change-Id: Ib1fdb266204649c82af0a28ccaf4fdafb61ba34b
Merge "Require "libs" for MapReduce and Java jobs and disallow "mains""
Merge "Updated from global requirements"
Merge "Add an hdfs data source example to the rest doc"
Merge "Fixed potential problems in test_periodic.py"
Merge "Add a config flag to disable cluster deletion after integration test"