Added the flow static analysis tool

[jhs-panda]

Installed Flow with Babel and npm, and added files and updated package.json accordingly. Also flagged a file (api.js) to be checked when "npm run flow" is called in order to catch any errors.

A screenshot of my terminal output is shown below with the results of running Flow on the flagged file:

Output:
flowoutput.txt

[coveralls]

Pull Request Test Coverage Report for Build 8289539851

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.02%) to 85.191%

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Files with Coverage Reduction	New Missed Lines	%
src/notifications.js	1	82.91%
src/groups/join.js	1	92.05%
src/database/postgres/transaction.js	2	52.38%

Totals
Change from base Build 8289059259:	-0.02%
Covered Lines:	22702
Relevant Lines:	25409

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💛 - Coveralls