Mccalluc/data sets to plain data sets

[mccalluc]

and Fix #2014. (Looking at it, I realize this builds from #2020 instead of starting fresh. Not a big deal, but I apologize.)

[codecov-io]

Codecov Report

Merging #2021 into develop will increase coverage by 0.03%.
The diff coverage is 40%.

@@             Coverage Diff             @@
##           develop    #2021      +/-   ##
===========================================
+ Coverage    44.18%   44.22%   +0.03%     
===========================================
  Files          416      416              
  Lines        27744    27711      -33     
  Branches      1339     1339              
===========================================
- Hits         12259    12254       -5     
+ Misses       15485    15457      -28

Impacted Files	Coverage Δ
refinery/tool_manager/models.py	94.97% <ø> (ø)	⬆️
...ui/source/js/user-file-browser/services/factory.js	40.54% <ø> (ø)	⬆️
refinery/ui/source/js/commons/router/state.js	68.18% <ø> (ø)	⬆️
refinery/core/models.py	62.56% <ø> (ø)	⬆️
refinery/core/urls.py	100% <ø> (ø)	⬆️
refinery/ui/source/js/data-set-nav/state.js	70% <ø> (ø)	⬆️
...file-browser/ctrls/user-file-browser-files-ctrl.js	11.76% <ø> (ø)	⬆️
refinery/tool_manager/tests.py	99.79% <ø> (ø)	⬆️
...e/js/data-set-import/controllers/isa-tab-import.js	38.63% <0%> (ø)	⬆️
...e/js/data-set-import/controllers/metadata-table.js	21.71% <0%> (ø)	⬆️
... and 3 more

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