Make indigo pip-installable

[longhotsummer]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 891

• 187 of 200 (93.5%) changed or added relevant lines in 17 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 89.007%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
indigo_api/views/attachments.py	6	7	85.71%
indigo_api/models.py	23	25	92.0%
indigo_api/migrations/0055_document_expression_dates.py	12	14	85.71%
indigo_api/serializers.py	49	51	96.08%
indigo_api/views/public.py	11	17	64.71%

Files with Coverage Reduction	New Missed Lines	%
indigo_api/models.py	2	91.56%

Totals
Change from base Build 889:	0.02%
Covered Lines:	4089
Relevant Lines:	4594

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💛 - Coveralls