feat(jwt): Implement JWT strategy for authentication

[collinewait]

What does this PR do?

• It implements a JWT strategy for authentication.

Description of Tasks to be completed?

• Writing unit tests.
• returning a token upon user registration.
• implementing a custom backend JWT authentication.

How should this be manually tested?

• After cloning the repo, cd into the directory.

• Run pip install -r requirements.txt

• Use Postman to try out the endpoints.
  /api/users/ endpoint for registration. Data format:

      {
  "user": {
     "username": "xxxxx",
     "email": "x@y.com",
     "password": "testing"
     }
     }  
  
  

/api/users/login/ endpoint for login. Data format:

 {
"user": {
	"email": "x@y.com",
	"password": "testing"
    }
   }

/api/user/ endpoint to for getting a current user. Authentication is required so
add the token in the header section after login.

What are the relevant pivotal tracker stories?

• #159952000

Screenshots

• Mentainability on codeclimate:

[coveralls]

Pull Request Test Coverage Report for Build 175

• 104 of 104 (100.0%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.6%) to 95.399%

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Totals
Change from base Build 137:	2.6%
Covered Lines:	311
Relevant Lines:	326

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💛 - Coveralls

[inno-asiimwe]

Why do we have this line in our codebase yet it is commented out?

[collinewait]

I am to remove it.