res_pjsip_sdp_rtp: Add support for optimistic SRTP.

Optimistic SRTP is the ability to enable SRTP but not have it be
a fatal requirement. If SRTP can be used it will be, if not it won't be.
This gives you a better chance of using it without having your sessions
fail when it can't be.

Encrypt all the things!

Review: https://reviewboard.asterisk.org/r/3992/
........

Merged revisions 428222 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@428224 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/ast-db-manage/config/versions/945b1098bdd_add_media_encryption_optimistic_to_pjsip.py

@@ -0,0 +1,31 @@
+"""add media encryption optimistic to pjsip
+
+Revision ID: 945b1098bdd
+Revises: 15b1430ad6f1
+Create Date: 2014-11-19 07:47:52.490388
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '945b1098bdd'
+down_revision = '15b1430ad6f1'
+
+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('media_encryption_optimistic', yesno_values))
+
+
+def downgrade():
+    op.drop_column('ps_endpoints', 'media_encryption_optimistic')