Support a default context

[wasade]

It is annoying entering the context repeatedly. It would be great to have a default or to source from the environment but allow it to be overridden if the user specifies. Ie:

# in redbiom/__init__.py
def get_config():
    ...
    ctx = os.environ.get('REDBIOM_CONTEXT')

# in redbiom/command/__init__.py
def get_context(user_specified):
    if user_specified is None:
        import redbiom
        return redbiom.get_config()['ctx']
    else:
        return user_specified

...any redbiom/command/*.py method can then leverage get_context. Or, perhaps a click.option('--context', ...) callback so it's implicit.

[wasade]

I'm marking this as having server side support as one possible solution here is an API endpoint where the client asks for a context suggestion