Add support for mono 4.0?

[null4n]

mono version is Mono JIT compiler version 4.2.1

System.NotImplementedException: The method or operation is not implemented.
  at System.Management.ManagementClass..ctor (System.Management.ManagementPath path) <0x419ec030 + 0x00023> in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.Management.ManagementClass:.ctor (System.Management.ManagementPath)
  at FileExplorer.Utils.GetLogicProcessorCount (System.Int32& coreCount) <0x419ebd10 + 0x00077> in <filename unknown>:0 
  at FileExplorer.Utils.GetLogicProcessorCount () <0x419ebc70 + 0x00013> in <filename unknown>:0 
  at FileExplorer.DUWorker..ctor () <0x419eb970 + 0x0005b> in <filename unknown>:0 
  at FileExplorer.frmMain..ctor () <0x41945e50 + 0x00697> in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) FileExplorer.frmMain:.ctor ()
  at FileExplorer.Program.Main () <0x41904d90 + 0x0002f> in <filename unknown>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.NotImplementedException: The method or operation is not implemented.
  at System.Management.ManagementClass..ctor (System.Management.ManagementPath path) <0x419ec030 + 0x00023> in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.Management.ManagementClass:.ctor (System.Management.ManagementPath)
  at FileExplorer.Utils.GetLogicProcessorCount (System.Int32& coreCount) <0x419ebd10 + 0x00077> in <filename unknown>:0 
  at FileExplorer.Utils.GetLogicProcessorCount () <0x419ebc70 + 0x00013> in <filename unknown>:0 
  at FileExplorer.DUWorker..ctor () <0x419eb970 + 0x0005b> in <filename unknown>:0 
  at FileExplorer.frmMain..ctor () <0x41945e50 + 0x00697> in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) FileExplorer.frmMain:.ctor ()
  at FileExplorer.Program.Main () <0x41904d90 + 0x0002f> in <filename unknown>:0