"Feature-Fix"

So I caught some embarrassing bugs. Notably CDA/LDA had a transpose/broadcasting error that basically made it - well - it made the method not CDA/LDA. I also included some safeties for the GuassianDiscriminant classifier, so if a class covariance matrix is singular the null space is removed to force singularity(it also throws a warning).

Notably, I added LinearPerceptron classifiers, code to generate multivariate confidence ellipses for discriminant analysis methods, and updated some of the docs. This release is being cut mostly to test the new package registrator for Julia. I really want end users to get the latest version of the package when they use Pkg.add().