fix functions not working properly due to db changes

[hjusassac]

• [x] add challenges: Unknown column 'users_accomplished'

• add/edit challenges input fields need to be changed

  • [ ] 'content' field for both add/edit
  • [x] 'updated_date' field for edit

Plus,

• [ ] condition field 👉 should be optional input(since null is possible) 👉 this can be done after #22