res_pjsip: New endpoint option "refer_blind_progress"

This option was added to turn off notifying the progress details
on Blind Transfer. If this option is not set then the chan_pjsip
will send NOTIFY "200 OK" immediately after "202 Accepted".

Some SIP phones like Mitel/Aastra or Snom keep the line busy until
receive "200 OK".

ASTERISK-26333 #close

Change-Id: Id606fbff2e02e967c02138457badc399144720f2

contrib/ast-db-manage/config/versions/86bb1efa278d_add_ps_endpoints_refer_blind_progress.py

@@ -0,0 +1,30 @@
+"""add ps_endpoints.refer_blind_progress
+
+Revision ID: 86bb1efa278d
+Revises: 1d0e332c32af
+Create Date: 2017-05-08 16:52:36.615161
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '86bb1efa278d'
+down_revision = '1d0e332c32af'
+
+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_endpoints', sa.Column('refer_blind_progress', yesno_values))
+
+def downgrade():
+    op.drop_column('ps_endpoints', 'refer_blind_progress')