Fixed filtering of query histogram data by category.
separate database work from master
Fixed query tablular data display.

Saving job progress *after* saving cats.
Removed Epiphany dataset provider.

It's not used any more: instead, the file is downloaded and a
FileDatasetProvider is used.
Code style: made some of the akka workers code more readable.
change upper and lower as list
Merge remote-tracking branch 'origin/akka-workers' into akka-workers
Fixed bucket filter lists.

Needed to use inclusive boundary operators (<= and >=) instead of
exclusive (< and >).

Also updated code styling.
Hist objects can now have arbitrary buckets.

Re-wrote folding and updating for Hist objects. The generation of
the buckets is still static, but their use is more generic now.
Increased warmup rounds for categories benchmark test.

It wasn't showing repeatable results, but now it seems to.
Added methods to optimise foldable results.

I.e. to remove empty buckets and categories from Hist and Cats.
Optimising stats before saving to the database.

This removes all empty histogram buckets, resulting in far fewer
rows being written, and a speed-up for accessing stats data of
about 2 to 6x.