Split sahara into sahara-api and sahara-engine

Split monolitic sahara-api into two services: sahara-api and
sahara-engine. The former is a user-facing interface, the later -
service doing all the work. Sahara-api sends tasks to sahara-engine
via oslo.messaging. See the blueprint for details.

Notes:

* Used the following Climate RPC code as a baseline:
  https://github.com/stackforge/climate/blob/master/climate/utils/service.py
  hence added Julien Danjou to licence header.
* Removed the old contents of sahara/utils/rpc.py - that is a prehistoric
  stuff not used anywhere.
* sahara-api still depends on eventlet, while we want to drop this dependency
  in the end.
* periodics run in sahara-api. They shold be moved to engine later.

Partially Implements: blueprint scalable-savanna
Change-Id: I64275a757b539f3fcddd6e993d6614d492745226

requirements.txt

@@ -5,6 +5,7 @@ Flask>=0.10,<1.0
 iso8601>=0.1.9
 jsonschema>=2.0.0,<3.0.0
 oslo.config>=1.2.0
+oslo.messaging>=1.3.0
 paramiko>=1.9.0
 pbr>=0.6,!=0.7,<1.0
 requests>=1.1

sahara/utils/patches.py

@@ -55,6 +55,9 @@ def eventlet_import_monkey_patched(module):
 def patch_minidom_writexml():
     """Patch for xml.dom.minidom toprettyxml bug with whitespaces around text
 
+    We apply the patch to avoid excess whitespaces in generated xml
+    configuration files that brakes Hadoop.
+
     (This patch will be applied for all Python versions < 2.7.3)
 
     Issue: http://bugs.python.org/issue4147

setup.cfg

@@ -29,8 +29,9 @@ data_files =
 
 [entry_points]
 console_scripts =
+    sahara-all = sahara.cli.sahara_all:main
     sahara-api = sahara.cli.sahara_api:main
-    sahara-all = sahara.cli.sahara_api:main
+    sahara-engine = sahara.cli.sahara_engine:main
     sahara-db-manage = sahara.db.migration.cli:main
     _sahara-subprocess = sahara.cli.sahara_subprocess:main
 
@@ -46,6 +47,10 @@ sahara.infrastructure.engine =
 sahara.remote =
     ssh = sahara.utils.ssh_remote:SshRemoteDriver
 
+sahara.run.mode =
+    all-in-one = sahara.service.ops:LocalOps
+    distributed = sahara.service.ops:RemoteOps
+
 [build_sphinx]
 all_files = 1
 build-dir = doc/build