provide UI control for NSX plugin 'replication_mode' setting
provide UI control for NSX plugin 'replication_mode' setting

- NSX cluster can operate without NSX Service nodes, but this requires
  configuration of `replication_mode' setting, so lets add an
  opportunity for user to specify that his NSX cluster runs in testing
  mode (without Service nodes).

Change-Id: Ia545dd90fd7e8b3b2de7280088bd07c689b1adb7
Partial-bug: #1365043

eayunstack/fuel-web,huntxu/fuel-web,huntxu/fuel-web,prmtl/fuel-web,nebril/fuel-web,zhaochao/fuel-web,nebril/fuel-web,prmtl/fuel-web,huntxu/fuel-web,eayunstack/fuel-web,prmtl/fuel-web,nebril/fuel-web,stackforge/fuel-web,stackforge/fuel-web,eayunstack/fuel-web,nebril/fuel-web,stackforge/fuel-web,SmartInfrastructures/fuel-web-dev,zhaochao/fuel-web,huntxu/fuel-web,nebril/fuel-web,zhaochao/fuel-web,SmartInfrastructures/fuel-web-dev,zhaochao/fuel-web,prmtl/fuel-web,huntxu/fuel-web,SmartInfrastructures/fuel-web-dev,SmartInfrastructures/fuel-web-dev,eayunstack/fuel-web,SmartInfrastructures/fuel-web-dev,prmtl/fuel-web,zhaochao/fuel-web,eayunstack/fuel-web