Add continuously optimization

This patch set adds implementation for CONTINUOUS type
of audit.

Change-Id: I5f4ec97b2082c8a6b3ccebe36b2a343fa4a67d19
Implements: blueprint continuously-optimization

watcher/db/sqlalchemy/models.py

@@ -177,6 +177,7 @@ class Audit(Base):
     audit_template_id = Column(Integer, ForeignKey('audit_templates.id'),
                                nullable=False)
     parameters = Column(JSONEncodedDict, nullable=True)
+    interval = Column(Integer, nullable=True)
 
 
 class Action(Base):