Time in error messages is not understandable

Time in error messages is shown in seconds, so if min-max interval is in days or years it looks like: ...period: must be between "86400" and "788400000", which is not quite human readable. So I suggest convert seconds to units most suitable for particular situation, or at least write units symbols after numbers.

Perfect fix: ...period: must be between "1d" and "25Y"
Acceptable fix: ...period: must be between "86400s" and "788400000s"

For example Steps to reproduce:
1. Open Administration -> General -> Housekeeping
2. Change Data storage period for Services to value smaller than 1 day
3. Press Update