Front end that can use DataFrames and Formulas.

[doobwa]

This pull request is just a proof-of-concept for using the JuliaData project in concert with glm.jl. I included an example in test/glmFit.jl. Please let me know what you think.

One of the major things missing in this example is the ability to construct sparse design matrices using DataFrames as you have done with indicators(). (This is a feature I plan to work on sooner rather than later.) DataFrames also currently lacks a more general treatment of contrasts, and I'd be very interested in hearing your views on the matter. This pull request is simply to start the conversation!

[dmbates]

Thanks, Chris. Now incorporated. Eventually I would like to divide the work in fitting models based on model matrices (lm, aov, glm, lmer, glmer) into the predictor module and the response module where the predictor module can be dense, sparse or distributed.