Removed deadline, version, extra & host_aggregate

As we are about to version the Watcher objects, we need to make sure
that upcoming model/object modifications are additive in order to
avoid having to bump the major version of the API. Therefore,
this changeset removes 4 unused DB fields that were exposed in their
associated Watcher objects (i.e. AuditTemplate and Audit).

Change-Id: Ifb0783f21cd66db16b31e3c8e376fc9d6c07dea3
Partially-Implements: blueprint watcher-versioned-objects

doc/source/image_src/plantuml/sequence_overview_watcher_usage.txt

@@ -4,7 +4,7 @@ actor Administrator
 
 == Create some Audit settings ==
 
-Administrator -> Watcher : create new Audit Template (i.e. Audit settings : goal, scope, deadline,...)
+Administrator -> Watcher : create new Audit Template (i.e. Audit settings : goal, scope, ...)
 Watcher -> Watcher : save Audit Template in database
 Administrator <-- Watcher : Audit Template UUID
 

doc/source/image_src/plantuml/watcher_db_schema_diagram.txt

@@ -41,9 +41,7 @@ table(audit_templates) {
     uuid : String[36]
     name : String[63], nullable
     description : String[255], nullable
-    host_aggregate : Integer, nullable
-    extra : JSONEncodedDict
-    version : String[15], nullable
+    scope : JSONEncodedList
 
     created_at : DateTime
     updated_at : DateTime
@@ -59,10 +57,9 @@ table(audits) {
     uuid : String[36]
     audit_type : String[20]
     state : String[20], nullable
-    deadline : DateTime, nullable
     interval : Integer, nullable
     parameters : JSONEncodedDict, nullable
-    host_aggregate : Integer, nullable
+    scope : JSONEncodedList, nullable
 
     created_at : DateTime
     updated_at : DateTime