#159752185 Fix http_headers_already_set error

[olusoladavid]

What does this PR do?

Fix http_headers_already_sent Expressjs error due to double callbacks from async controllers

Description of Task to be completed

• Refactor async controllers to use async/await for cleaner logic
• Fix double callback error points

How should this be manually tested?

• Review code changes to server/controllers
• Pull branch into repo and run npm test

What are the relevant pivotal tracker stories?

#159752185

[coveralls]

Pull Request Test Coverage Report for Build 123

• 63 of 69 (91.3%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+10.5%) to 91.892%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
server/index.js	3	4	75.0%
server/controllers/userController.js	24	25	96.0%
server/controllers/entryController.js	32	36	88.89%

Totals
Change from base Build 122:	10.5%
Covered Lines:	142
Relevant Lines:	149

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💛 - Coveralls