Pluggable vdc.sh

vdc.sh was a morisic script to setup and show screen window for development. The file had to be changed every time when the developer wants to add new screen window or remove existing window.

vdc.sh has been modified to allow developers to customize windows and processes without changing vdc.sh file. Modulesfile is the new configuration file which controls screen windows to come up. The format is just having the list of window names with a few arguments sometime.

Modulesfile:
```
hva hva_id=demo1 host=192.168.1.1
#hva hva_id=demo2 host=192.168.1.2
zfs-sta
```

*tests/vdc.sh.d/modules.d* folder contains sub-folders they are same as the name of screen window. Each sub-folders have set of small scripts to setup or show screen window for the process on the window.