Add LinearRegression class.

* Add classifiers directory.
* Add initialization class for LinearRegression.
* Make data variable accessible to the class instance.
Complete LinearRegression class.

* Add predict method.
* Add algorithm to predict/classify output variable.
* add helper methods to help with prediction method.
Add exceptions to improper training set.

* Raise exception if training set is empty.
* Raise exception if training set has malformed data.
Add testing gems.

* Add rspec
* Add capybara for integration testing.
* Add database_cleaner for proper setup/teardown.
* Add factory_girl.
Add /spec and spec_helper.rb configuration.
Add RSpec tests for LinearRegression model.
Merge pull request #2 from dman7/add-linear-classification-algorithm-1

Add linear classification algorithm 1