Moved some MXNet-related code to CNNArch2MXNet and CNNArch2Gluon

2 jobs for develop in 5 minutes and 46 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Windows
passed #431262
Windows10
masterJobWindows

00:04:01

 
  Linux
passed #431263
BranchJobLinux

00:01:45