Versionner repository moved to PharoExtras

Hi,

I just moved the Versionner repository from http://smalltalkhub.com/#!/~demarey/Versionner/ to http://smalltalkhub.com/#!/~PharoExtras/Versionner/.
It will ease contributions and it will be easier to find with other tools / library of Pharo.

Regards,
Christophe.