res_pjsip: disable multi domain to improve realtime performace

This patch added new global pjsip option 'disable_multi_domain'.
Disabling Multi Domain can improve Realtime performance by reducing
number of database requests.

ASTERISK-25930 #close

Change-Id: I2e7160f3aae68475d52742107949a799aa2c7dc7

contrib/ast-db-manage/config/versions/8d478ab86e29_pjsip_add_disable_multi_domain.py

@@ -0,0 +1,31 @@
+"""pjsip_add_disable_multi_domain
+
+Revision ID: 8d478ab86e29
+Revises: 1c688d9a003c
+Create Date: 2016-04-15 11:41:26.988997
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '8d478ab86e29'
+down_revision = '1c688d9a003c'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ENUM
+
+YESNO_NAME = 'yesno_values'
+YESNO_VALUES = ['yes', 'no']
+
+def upgrade():
+    ############################# Enums ##############################
+
+    # yesno_values have already been created, so use postgres enum object
+    # type to get around "already created" issue - works okay with mysql
+    yesno_values = ENUM(*YESNO_VALUES, name=YESNO_NAME, create_type=False)
+
+    op.add_column('ps_globals', sa.Column('disable_multi_domain', yesno_values))
+
+
+def downgrade():
+    op.drop_column('ps_globals', 'disable_multi_domain')