Moved URL user_landing logic from template to view

Previously, the links for each of the notes/issues in the user_landing view were being generated by the template, which also created code duplication and made it hard to test. Have refactored the user_landing view so that the URLS are generated by the view and passed into a dictionary (e.g., 'attributes': issue, 'issue_url', url). This should increase efficiency and make it easier to test. It also eliminated a bunch of code duplication in template.