FIX
"Stadium settings: non-validated
     fields (negative values)"
     "Stadium settings: ""row"",
     ""place"", ""price"" fields validation
     (long data)"
     "Stadium settings: non-validated
     ""price"" field (any letters)"
     "Stadium settings: ""sector name"",
      ""row"", ""place"", ""price"" fields
     validation (""0"" value)"
     "Booking creation: unneed field
     "