simpler action creation
added notebook on first basic concepts
added context support hooks to proxy_core
added a ContextManagerAdapter to proxy.py
Merge branch 'context_sandbox' into develop
now notebook biobank-basics-01 shows also how to use the sandbox context manager
added missing Sandbox context manager.
Centralized biobank client configuration used by notebooks in .biobank
Now all notebooks rely on env variables for their configuration.
Merge branch 'notebooks' into develop

Moving to centralized parameters setting, some minor formatting changes
in the notebooks examples.
added exome_map_well_vids.py
Check if a collection edge exists before creating a new one

fixes #744
Merge branch 'bug_744' into develop