Override functions from StatsBase

[nalimilan]

In the perspective of adding Bootstrap.jl to the list of default packages in Stats.jl (JuliaStats/StatsKit.jl#4), it would be nice to use the confint and stderror functions from StatsBase instead of ci and se, and to add a method to StatsBase.nobs instead of defining a separate function.

[juliangehring]

Thanks for raising this, I wasn't aware of Stats.jl. I fully agree with your suggestions, the package can and should integrate better with StatsBase. I'll try to add these soon (possibly in combination with other interface related changes).

[juliangehring]

Since nobs is only used internally by the Bootstrap package, is having a general nobs in StatsBase very relevant? I'm not sure if there is a wide use for these methods; but if there is a broader interest, I'm happy to have it live in StatsBase.

[nalimilan]

Thanks. If nobs is internal then it's fine to keep it as is. It can always be exported later if needed.

[juliangehring]

Alright, all the renaming has been merged with #24.