Make the path in etcd customisable

[Fabszn]

Today, the path in etcd doesn't be modifiable. It is hardcoded in the source code ("constructR")
I think it could be useful to allow one customisation of this path.
This issue regards only root and the subdirectories but not the final key.
Use case : Some companies want to organise their etcd and give a formal structure of their etcd's threes