upgrade to hapi v16

[zoe-1]

https://github.com/hapijs/hapi/issues/3323

dependencies to update

• [x] hapi 15.x.x -> 16.x.x
• [x] joi 9.x.x -> 10.x.x

branch update status

• [x] master
• [x] assignment8
• [x] assignment7
• [x] assignment6
• [x] assignment5
• [x] assignment4
• [x] assignment3
• [x] assignment2
• [x] assignment1