Save working hours

[zviryatko]

finally the working hours will be send, so need to save it per user and connect them with screenshots.

It will be as json string in POST request with key messages, json example:

{
  [
    {"from": 1234567, "to": 1234568},
    {"from": 1234569, "to": 1234570},
    {"from": 1234571, "to": 1234572},
  ]
}

from, to is UNIX timestamp.