Fixed filtering issue; fixed modal issue for inperson job; bubbled json error to UI

- "unchecking a category filter clears all filters despite UI showing items in selections (resulting table display ignores hideInPerson, top left selections). Should respect current selections" - Put a check in for array.length = 0, which fixed the issue;
- "When JSON has an error (can test by adding text below in studentJobs.json in errors array and restarting tomcat), the error string is not shown to the user." - Added a method that looks for errors in the JSON file and returns an error on screen;
- "clicking job title of an in-person job refreshes page instead of doing modal pop-up of job description " - Issue with the element not being seen @ page load due to display: none. Added delegation so event can occur on button click
Added error output to HTML