Make Bernoulli produce Bools

[MikeInnes]

This effectively reverts #1048 and also addresses the original issue #984.

I'm not that familiar with this codebase, but it appears that rand(D, ...) uses the eltype of the distribution to create the right array container. For Bernoulli, eltype hit a fallback method that incorrectly returned Int64, so changing that to Bool fixes the issue.

[matbesancon]

tests failing at:
https://travis-ci.org/JuliaStats/Distributions.jl/jobs/655002051#L601

[MikeInnes]

The cdf and ccdf functions were previously incorrect (but not tested since the Int rather than Bool versions got called).

[ararslan]

Thanks, I think this makes much more sense to use Bools here.

[codecov-io]

Codecov Report

Merging #1079 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1079      +/-   ##
==========================================
+ Coverage   80.62%   80.68%   +0.05%     
==========================================
  Files         113      113              
  Lines        5611     5612       +1     
==========================================
+ Hits         4524     4528       +4     
+ Misses       1087     1084       -3

Impacted Files	Coverage Δ
src/univariate/discrete/bernoulli.jl	93.1% <100%> (+5.38%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d521695...b732ab2. Read the comment docs.

[cossio]

After this PR, will rand(Bernoulli(0.5), 5,5) produce a BitArray?

[MikeInnes]

@cossio not currently, since array generation just uses a fallback that creates an array based on the eltype. I'm sure that could be changed without too much difficulty later, but that should have its own discussion (I would be hesitant).

@matbesancon anything left to do for this to get merged and tagged?

[matbesancon]

yes all good it seems, I wanted a last patch release before this one, which is now on the way