Added private keys to series data in LoadAllSeries and added tests in th...

...e corresponding test
The current  TestLoadAllSeries() is pretty straightforward and small, whereas the new, table-driven version, is really long, significantly more complex and duplicates a lot of code from other table-driven tests. I think in this case we'd be better off writing two new tests, but I'm also not sure testing LoadAllSeries() with all those key combinations adds much value as they're all exercising the exact same code paths.