SympaStub

To avoid contacting the SympaSOAP Server I added a stubbed SympaClient, which returns some reasonable realistic values and should do for the moment.
index.js decides upon presence of some env-settings if it uses the stub or not. This should be done by some ncong settings some time later.
The groups module does not display dummy lists any longer, that is done by the appropriate subpages.
I adapted the groups_test.js accordingly