In preparation for reading the config also from a taskrc file I want to
simplify the configuration management beforehand. There should be one
place where we grab it from the environment, one place to grab from CLI
and then one place from conf file. This helps with simplifying a little
by not again injecting defaults at the mid-point.
Ultimately, we should create one 'config' data structure, probably dict
or NameSpace which we pass around and each function receives it.