Example of getting all certificates urls (#28)
Example of getting all certificates urls (#28)

* getting all certificates urls
* delete redundant line

* remove json import

* optimization via api/courses

* remove renundant functions

* back to api/certificates
added function to get user id

* simple html

* pep8 fixes

* html tags refactoring

* variable names refactoring

StepicOrg/Stepic-API