Address breaking change on nightly

[Nosferican]

Fix to 225

[TotalVerb]

Let's wait for Compat to support this so this can be done as using Compat.Dates.

[TotalVerb]

ref JuliaLang/Compat.jl#413

[andreasnoack]

The new version of Compat is now in METADATA so this can be updated

[andreasnoack]

I think you also need a using Compat.Dates

[Nosferican]

@nalimilan is the using Compat.Dates required as well? The documentation in Compat wasn't very clear on it, but let double check.

[nalimilan]

Yes, you need to replace Base.Dates with Compat.Dates everywhere it appeared. So I now realize JuliaData/Missings.jl#56 didn't change anything to the problem.

[nalimilan]

Regarding the case at hand, you just need to replace Dates with Compat.Dates on this line:

JSON.jl/src/Writer.jl

Line 52 in b4a4e33

Dates.TimeType, Char, Type, AbstractString, Enum, Symbol}

[Nosferican]

Let us check change it and check Travis. After the manual fix both packages compiled so the CI should be cleared.

[stevengj]

There's no performance difference between using Dates and import Dates (followed by qualified names). As long as there are no namespace collisions, I think using Dates is fine.

[TotalVerb]

Hi @Nosferican, thank you for the contribution! I went ahead and removed the if isdefined(...) line as mentioned in a review above. I agree that importing/using Dates is not a big deal, so this LGTM once CI passes.