adding inverse gamma distribution
adding inverse gamma distribution
Merge branch 'inversegamma' of https://github.com/danmerl/Distributions.jl into inversegamma

Conflicts:
	src/Distributions.jl
fixing dumb bugs, adding cdf for inverted gamma rvs
adding modes function and adding more efficient rand! for invertedgamma
Adding quantile function and reparametrizing so things are consistent between the gamma and inverse gamma implementations.
Merge pull request #30 from danmerl/inversegamma

Adding InvertedGamma random variables