Time crate serialization support

[Anfid]

Currently all date and time types are handled with chrono crate, however it's not the only time crate that other projects use and requiring extra type conversion and pulling another dependency for serializing time types is not optimal. I propose to implement support for both time and chrono crates.

I'm willing to implement serialization support for time crate and move both time and chrono behind a feature. This would be a breaking change.