create challenge modules

[bnguyenngoc]

a challenge has:

• a title
• a description
• a category
• number of points
• translations (en/fr) for points mentioned above

in challenges page
a user can:

• view challenges
• submit challenge for review
• sort challenges by title, number of points, state of challenge

an admin can:

• create a challenge
• edit the challenge
• delete the challenge
• sort challenges
• view teams who completed a challenge