[WIP] [MLLIB] Ordinary least square implementation

__This is work in progress__

Along with other statistical summaries we are interested in getting summary statistics for a linear regression model:
* Standard deviation of estimated parameters
* t-statistic and p-value for testing if estimated parameters may be equal to zero
* R-squared and Adjusted R-squared
Also possibly:
* AIC
* Leverage

We will be using SVD to solve the OLS and estimate above statistics.