Integrate Rally & Alembic

Alembic allows us to change in future DB schema,
which we are going to do soon.

This patch adds under rally/common/db/sqlalchemy/migrations
required files for alembic as well as a first init migrations
that was autogenerated from models that we have.

As well this patch adds CLI commands for DB management

Change-Id: I7caa090aa5c4c6563b7e34d0d09baa039a3aa718
Co-Authored-By: Illia Khudoshyn <ikhudoshyn@mirantis.com>

.coveragerc

@@ -5,3 +5,4 @@ source = rally
 [report]
 ignore_errors = True
 precision = 3
+omit = */migrations/versions/ca3626f62937_init_migration.py

doc/source/index.rst

@@ -33,6 +33,7 @@ Contents
    user_stories
    plugins
    plugin/plugin_reference
+   db_migrations
    contribute
    gates
    feature_requests

requirements.txt

@@ -1,6 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
+alembic>=0.8.0 # MIT
 Babel>=1.3 # BSD
 boto>=2.32.1 # MIT
 decorator>=3.4.0 # BSD

tests/unit/test.py

@@ -31,10 +31,10 @@ class DatabaseFixture(fixture.Config):
     def setUp(self):
         super(DatabaseFixture, self).setUp()
         db_url = os.environ.get("RALLY_UNITTEST_DB_URL", "sqlite://")
-        db.db_cleanup()
+        db.engine_reset()
         self.conf.set_default("connection", db_url, group="database")
-        db.db_drop()
-        db.db_create()
+        db.schema_cleanup()
+        db.schema_create()
 
 
 class TestCase(base.BaseTestCase):