updates enum capitalization to be more consistent with Julia style

[ssfrr]

I don't think there's anywhere else where we use all-caps for a type name. Also in one place we had the enum values capitalized. This brings the docs in-line with what's used in the tests.

[nalimilan]

For the type indeed camel case is the convention. Though for values, constants are often written in all caps. See for example those under LibGit2.Consts. It would be good to choose a common convention for constants and enums.

[StefanKarpinski]

We definitely do need to pick a common convention.

[nalimilan]

@StefanKarpinski But if you don't make that choice, who will? ;-)

[tkelman]

+1 for this, but needs rebase

[JeffBezanson]

+1

[ssfrr]

thanks for the bump on this, I'm updating now. should I skip CI on this to save travis time, or run so the doctest change gets tested?

[KristofferC]

Queue doesn't look that bad so I think running through CI should be fine.

[ssfrr]

Travis is failing with errors like:

du: cannot access `/tmp/julia/*': No such file or directory

[tkelman]

that was #19848 - logs would have looked the same as https://travis-ci.org/JuliaLang/julia/builds/188622631, restarted here

[ssfrr]

now it's just failing on 32-bit linux with a bunch of errors like:

Error in testset dsp:
Error During Test
  Test threw an exception of type ProcessExitedException
  Expression: dsp
  ProcessExitedException()

with various things substituted for dsp