Actually *add* the database schema management utilities

In r397874, the scripts were removed... but not replaced. Thanks to
Michael Young for noticing this!
........

Merged revisions 397911 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@397912 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/ast-db-manage/voicemail/script.py.mako

@@ -0,0 +1,22 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision}
+Create Date: ${create_date}
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}