Created test cases for user registration API

[aditya-garg-09-01-2002]

it checks if various scenarios can be satisfied with the API

• Creation of test cases for the following scenarios
  • when new user id is provided
  • when existing but unverified user tries to do the registration
  • when verified attempts registration
• testing for mail is not integrated, to be done with mock api or mail trap
• testing upgrades for database so database don't change in actual sense

Issue Reference: #5

[aditya-garg-09-01-2002]

Issue is not closed for the following

• testing for mail using mailtrap or mock api.
• testing is causing database to update, which must be reverted after completion of test.