ncm-ceph: fix for SSH multiplexing when using old SSH version

supplies a fix for  #321 

using `no_controlpersist` self var is only solution without refactoring a lot of subs .. (`$gvalues` does not go deep enough)

EL6.6 will have an updated SSH version with support for `ControlPersist`
Easier to read:

```perl
qw(-o ControlMaster=auto -o ControlPersist=600 -o ControlPath=/tmp/ssh_mux_%h_%p_%r);
```