Added shadow fading component.
Added support for shadow fading component "s"
"s" can be enabled/disabled using "-ns3::SUIPathLossModel::EnableShadowing" Attribute
Minor Changes
Merge pull request #4 from kushalsp007/master

Merge pull request #1 from deepaknadig/master
Merge pull request #2 from deepaknadig/master

Models version 1.1