Create Market from Sublet

[vcai122]

Created market from sublet (but kept the git blame intact, I'm 90% sure...)

The plan should be to make all necessary changes for market here, then ship both to production. Then manually have a script copy over the current data that is live in sublet before deleting the sublet code.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 351 lines in your changes missing coverage. Please review.

Project coverage is 79.94%. Comparing base (d2e691c) to head (316e43a).

Files with missing lines	Patch %	Lines
backend/market/views.py	0.00%	183 Missing ⚠️
backend/market/serializers.py	0.00%	81 Missing ⚠️
backend/market/models.py	0.00%	41 Missing ⚠️
backend/market/permissions.py	0.00%	25 Missing ⚠️
backend/market/admin.py	0.00%	13 Missing ⚠️
backend/market/urls.py	0.00%	8 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #315       +/-   ##
===========================================
- Coverage   90.37%   79.94%   -10.43%     
===========================================
  Files          62       68        +6     
  Lines        2681     3032      +351     
===========================================
+ Hits         2423     2424        +1     
- Misses        258      608      +350     

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