Routes user refactor

[ghost]

• changed user views according to Remove ids from **user** update and delete routes #67 Rename users routes to user #69 Move ids from URL to body in **user**'s routes #71
• edited documentation accordingly
• improved the correspongding controller methods according to Return more detailed response from controllers #72
• changed authorization methods to reflect those changes
• authorization additionally returns codeand msg in case of a failure
• more appropriate error code
• changed tests to work with these changes
• added 2 new test utility functions delete_user_for_test_cases and create_access_token_for_test_cases
• added app context which was necessary for creating a token (this broke create project test which needs to bechanged anyways with the impending refactoring of those routes.
• removed create user route and corresponding tests as this is only done by the register and login routine
• removed the /getcurrentuser route from Change link models to JSON string #57 this is now the /user route
  closes Remove ids from **user** update and delete routes #67
  closes Rename users routes to user #69
  closes Move ids from URL to body in **user**'s routes #71
  closes Get current user route #56