tags should be coerced to lowercase strings

[delgadom]

name/case conflicts, type mismatch, and other issues are popping up. getting this right is critical to making DataFS usable.

[jgerardsimcock]

Two parts of this issue as far as I can see.

1. A script to go through all archives and coerce all tags to lower case strings.
2. Changes to api.manager._set_tags that coerces all tags to lower case strings.

Going to open another issue that address #2. 1 is easy enough but would prefer feedback before I go ahead and implement this.

[delgadom]

This sounds great. I think the script is pretty straightforward, with a couple tweaks for our specific use case.

For one, dynamo seems to have coerced all floats to Decimal-precision values, so I'd want to check to make sure, e.g., that Decimal('2.01') gets converted to '2.01' not "Decimal('2.01')"!