Fixed variance of MixtureModel
Passed on normalized probabilities to AliasTable
added support in variance for multivariate distributions
Add support for vom Mises distribution

The initial implementation supports standard moments, pdf, cdf, and drawing
samples.

To support large concentrations, the scaled bessel function implementation
had to be used. This scaled version is currently not supported in Base,
such that its support is currently added only for the von Mises distribution.
Add von Mises distribution to documentation

Added description of constructors to univariate distribution
documentation. Also, renamed support to helper functions in vonmises.jl
Addressing issue JuliaStats/Distributions.jl#223

The support of the distribution was not defined, as AngularDistribution or
CircularDistribution class does not exist, yet.
Merge remote-tracking branch 'upstream/master' into addvonmises
Updated rand! for mvtdist (was broken after NumericExtensions was removed from REQUIRE)
Removed bdivide! from rand! in mtvdist too
Used broadcast! to replace bdivide! and badd! in rand! of mvtdist
Binomial TPE sampler, KS test for discrete vars
Merge remote-tracking branch 'upstream/master' into addvonmises
Removed besselix implementation, as now part of julia/base
Add Poisson samplers
Sampler type, Gamma samplers
Merge pull request #245 from JuliaStats/binom-rand

Sampler abstract type, implement julia Binomial and Poisson samplers.
rearrange Exponential methods
typo
sampler types moved to StatsBase
categorical samplers migrated out to StatsBase