Add a dynamic loading of the Watcher Planner implementation

In watcher, an audit generates a set of actions which
aims at achieving a given goal (lower energy consumption, ...).
It is possible to configure different strategies in order to achieve
each goal. Each strategy is written as a Python class which produces
a set of actions. Today, the set of possible actions is fixed for a
given version of Watcher and enables optimization algorithms to
include actions such as instance migration, changing hypervisor state,
changing power state (ACPI level, ...).

The objective of this patchset is to give the ability to extend the
default set of planner algorithms currently available in Watcher
using Stevedore.

The doc need to explain how create a new planner.

DocImpact
Partially implements: blueprint watcher-add-actions-via-conf

Change-Id: I2fd73f8c4a457ee391d764a7a3f494deecd2634f

etc/watcher/watcher.conf.sample

@@ -91,7 +91,7 @@
 
 # List of logger=LEVEL pairs. This option is ignored if
 # log_config_append is set. (list value)
-#default_log_levels = amqp=WARN,amqplib=WARN,boto=WARN,qpid=WARN,sqlalchemy=WARN,suds=INFO,oslo.messaging=INFO,iso8601=WARN,requests.packages.urllib3.connectionpool=WARN,urllib3.connectionpool=WARN,websocket=WARN,requests.packages.urllib3.util.retry=WARN,urllib3.util.retry=WARN,keystonemiddleware=WARN,routes.middleware=WARN,stevedore=WARN,taskflow=WARN
+#default_log_levels = amqp=WARN,amqplib=WARN,boto=WARN,qpid=WARN,sqlalchemy=WARN,suds=INFO,oslo.messaging=INFO,iso8601=WARN,requests.packages.urllib3.connectionpool=WARN,urllib3.connectionpool=WARN,websocket=WARN,requests.packages.urllib3.util.retry=WARN,urllib3.util.retry=WARN,keystonemiddleware=WARN,routes.middleware=WARN,stevedore=WARN,taskflow=WARN,keystoneauth=WARN
 
 # Enables or disables publication of error events. (boolean value)
 #publish_errors = false
@@ -127,10 +127,6 @@
 # MatchMaker driver. (string value)
 #rpc_zmq_matchmaker = redis
 
-# Use REQ/REP pattern for all methods CALL/CAST/FANOUT. (boolean
-# value)
-#rpc_zmq_all_req_rep = true
-
 # Type of concurrency used. Either "native" or "eventlet" (string
 # value)
 #rpc_zmq_concurrency = eventlet
@@ -157,8 +153,13 @@
 # timeout exception when timeout expired. (integer value)
 #rpc_poll_timeout = 1
 
-# Configures zmq-messaging to use broker or not. (boolean value)
-#zmq_use_broker = false
+# Configures zmq-messaging to use proxy with non PUB/SUB patterns.
+# (boolean value)
+#direct_over_proxy = true
+
+# Use PUB/SUB pattern for fanout methods. PUB/SUB always uses proxy.
+# (boolean value)
+#use_pub_sub = true
 
 # Minimal port number for random ports range. (port value)
 # Minimum value: 1
@@ -633,17 +634,6 @@
 # Deprecated group/name - [DEFAULT]/amqp_auto_delete
 #amqp_auto_delete = false
 
-# Send a single AMQP reply to call message. The current behaviour
-# since oslo-incubator is to send two AMQP replies - first one with
-# the payload, a second one to ensure the other have finish to send
-# the payload. We are going to remove it in the N release, but we must
-# keep backward compatible at the same time. This option provides such
-# compatibility - it defaults to False in Liberty and can be turned on
-# for early adopters with a new installations or for testing. Please
-# note, that this option will be removed in the Mitaka release.
-# (boolean value)
-#send_single_reply = false
-
 # SSL version to use (valid only if SSL enabled). Valid values are
 # TLSv1 and SSLv23. SSLv2, SSLv3, TLSv1_1, and TLSv1_2 may be
 # available on some distributions. (string value)
@@ -672,7 +662,7 @@
 # replies. This value should not be longer than rpc_response_timeout.
 # (integer value)
 # Deprecated group/name - [DEFAULT]/kombu_reconnect_timeout
-#kombu_missing_consumer_retry_timeout = 5
+#kombu_missing_consumer_retry_timeout = 60
 
 # Determines how the next RabbitMQ node is chosen in case the one we
 # are currently connected to becomes unavailable. Takes effect only if
@@ -803,3 +793,13 @@
 # strategy (for example: BASIC_CONSOLIDATION:basic,
 # MY_GOAL:my_strategy_1) (dict value)
 #goals = DUMMY:dummy
+
+
+[watcher_planner]
+
+#
+# From watcher
+#
+
+# The selected planner used to schedule the actions (string value)
+#planner = default