[model zoo] ignore models -- only for reference or zoo

.gitignore

@@ -51,6 +51,7 @@ Makefile.config
 # 1. reference, and not casually committed
 # 2. custom, and live on their own unless they're deliberated contributed
 data/*
+models/*
 *.caffemodel
 *.solverstate
 *.binaryproto