normalize_keys regression in version 2.10.0

[d70-t]

In dca87fc (#793), the normalize_keys parameter default of FSStore has been changed back to from False to True (see here). This reverts #755 and recreates the issue of #739.

I didn't find a comment on this in the commit message and believe this was done by accident.

[joshmoore]

Thanks, @d70-t for all the sleuthing, and sorry if I let something slip through. @d-v-b: can you say if it was intentional or not?

[d-v-b]

this looks like my mistake! I can whip up a quick fix.

[d-v-b]

see #842