Support for Symmetric Paths

- When user creates a service path and service chain has symmetric set to "true"
  then SFC Provider will create two RSPs.
-  Basically when a SFP is created, Provider will:

*   1 - Create RSP
*   2 - Add Path to SFF State
*   3 - Add path to SF state
*   4 - Check if Chain is symmetric
*   5 - if chain is symmetric repeat 1-3 for reverse path

Change-Id: Ie38808a48c4d2d8132bf82ea4337e1e5712ff1de
Signed-off-by: Reinaldo Penno <rapenno@gmail.com>