BUGFIX: allow inline reweighting configuration
In !519 (merged) I broke the ability to specify the reweighting configuration directly in the ini file, e.g.,
reweighting-configuration={"likelihood-type": "GravitationalWaveTransient"}
This MR fixes that broken behaviour and also improves the usability with file transfers as if a reweighting config file is passed, that is read and stored in the data dump and so we don't have to worry about transferring an additional file.
@gregory.ashton I'm not sure exactly what the best way to add things to the data dump is, but I figured it seemed like something that would fit naturally in meta data.