Make home config version dependent

[dmaluenda]

Is your feature request related to a problem? Please describe.
Nowadays, Scipion is cumulating several versions and users usually want to keep old vesions for just in case or even to be able to recover some specific results (for comparision, papers in peer-review process...). Therefore, one should be carefull with the home-config file in order to match with the Scioion opened.

Describe the solution you'd like
I propose to make home-config pathfile dependent of Scipion version. For example:

~/.config/scipion/scipion_vXXXX.conf

where XXXX is the version number released.

Describe alternatives you've considered
I know that it can be solved by expprting the SCIPION_HOME_CONFIG env.var. and this can be done in a alias. Moreover, one can use the scipion --config /path/to/whole/config/file.conf. However, I thing it would be more clear and user friendly in this way.