pjsip: Added "reg_server" to contacts.

If the Asterisk system name is set in asterisk.conf, it will be stored
into the "reg_server" field in the ps_contacts table to facilitate
multi-server setups.

ASTERISK-25931

Change-Id: Ia8f6bd2267809c78753b52bcf21835b9b59f4cb8

contrib/ast-db-manage/config/versions/81b01a191a46_pjsip_add_contact_reg_server.py

@@ -0,0 +1,25 @@
+"""pjsip: add contact reg_server
+
+Revision ID: 81b01a191a46
+Revises: 65eb22eb195
+Create Date: 2016-04-15 15:00:35.024525
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '81b01a191a46'
+down_revision = '65eb22eb195'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column('ps_contacts', sa.Column('reg_server', sa.String(20)))
+    op.drop_constraint(UniqueConstraint('id'), 'ps_contacts', type_='unique')
+    op.create_unique_constraint('ps_contacts_uq', 'ps_contacts', ['id','reg_server'])
+
+def downgrade():
+    op.drop_constraint('ps_contacts_uq', 'ps_contacts', type_='unique')
+    op.drop_column('reg_server')
+    op.create_unique_constraint(None, 'ps_contacts', 'id')