Add VPNaaS plugin codes for Quantum
* can add/update/delete/search site configure to/from SQL db
* can POST/PUT/DELETE/GET site(s) configure from REST API
* run_test.py db.vpn.test_db_vpn:TestVPNXML is passed
* TBD, configure path to VSE is not cover in this change
* TBD, should add support for isakmp_policy, ipsec_policy, trust_profile support
Add VPNaaS plugin codes for Quantum
* can add/update/delete/search site configure to/from SQL db
* can POST/PUT/DELETE/GET site(s) configure from REST API
* run_test.py db.vpn.test_db_vpn:TestVPNXML is passed
* TBD, configure path to VSE is not cover in this change
* TBD, should add support for isakmp_policy, ipsec_policy, trust_profile support
Push IPSec VPN configure into vShield Edge
a. add vpnapi to convert quantum API to VSM API
b. add vpnplugin to support vShield Edge
c. add create_site, update_site, get_site, delete_site test cases into test_vpn
Add stats support, the url is vpn/sites/<id>/stats
Change pri_networks format from string to a list of hash.
For example, the str format of pri_networks is
"192.168.1.0/24,192.168.2.0/24-192.168.11.0/24;192.168.3.0/24-192.168.33.0/24,192.168.44.0/24".
When converted to a list of hash, the format will be like below
'pri_networks' : [
            {
               'local_subnets': "192.168.1.0/24,192.168.2.0/24",
               'peer_subnets': "192.168.11.0/24"
            },{
               'local_subnets': "192.168.3.0/24",
               'peer_subnets': "192.168.33.0/24,192.168.44.0/24"
            }
        ]
Add VPNResttest and fix some minor errors
    1. Add The VPNaas REST API test in real Quantum environment
    2. Add update_site() VPNaas unittest implementation
    3. fix some minor update_site() implementation errors
remove vpn-resttest got from vpnaas branch
Check if LB enabled when creating a pool