Patch Version 1.0.11 : Modify VirtueMart patch to create a totally independent slave configuration file

The previous version of the patch for VirtueMart only allow to customise the site URL and all the other configuration parameters was common to all the website.

With this new patch, we have created a totally independent slave VirtueMart configuration file that allow to change any parameters of the slave virtuemart configuration.

When a slave site has not defined and save specific configuration values, this is the master virtuemart configuration file that is used.
In such maner that a virtuemart configuration always exists.
For a slave site, the master configuration must be considered as a the default slave configuration.
The slave site has it own configuration when it save it for the first time.