Simplified the generateRandomString method
Merge pull request #91 from Coenego/simplify-randomstring-method

Simplified the generateRandomString method
Added local storage functionality
Keep track of collapsed lists
Follow-up on review

- Provided additional comments
- Removed unnecessary key creation in local storage
- Moved the JSON functionality to the utility function
- Added extra unit tests
Simplified code
Removed previous collapsed modules from the local storage
Merge pull request #85 from Coenego/issue-85-collapse

Keep track of collapsed modules
Merge branch 'master' of https://github.com/CUL-DigitalServices/grasshopper-ui into adminUI
Admin UI: Adjust active page background-color in navigation list, restructure recursive functions to be more in line with others in the code, don't declare variable twice in student view index.js