[API] As a user, I can login

[mosharaf13]

Why

For user use to login before using application from API

Acceptance Criteria

• User can send POST JSON REST API to login with following information
  • Username
  • Password
• Client ID
• Client secret
• Respond with status 400 Bad request and error messages in case of failed authentication
• Respond with status 200 OK and should contain access token in case of successful authentication