Better output of test prediction in "Housing" model

[pavan-kalyan]

When the housing,jl file is run,the last line is not printed to the console (outputs correctly when run line by line).
Also the test example is currently the first record in the dataset, I think it would be better if we use a random record from the dataset to predict.
All of this can be implemented in 2-3 lines of code.
I can work on this if no one else is already working on this.

[pavan-kalyan]

Sorry, because of time constraints I wont be able to work on this.

[shreyas-kowshik]

Made changes in #98 .
Added support for train-test split according to the user rather than just a single test set element.