Implement file upload with tagging in UpStore

[carbontracking]

Allow users to upload files. All uploaded files must be tagged as

• public/private
• subject
• date
• school/year/class

Filetypes accepted

• any graphics format that can be viewed in a browser (jpeg/gif/bmp etc.)
• PDF file
• html file
• docx and OpenOffice files

[Rchatain]

Middleware / plugin required to upload files :

• (connect-)busboy
• multer
• Formidable
• body-parser (tried, not working actually)