Added function computeCostMulti.m, that compute cost function for linear regression whith multiple variables
Added function featureNormalize.m, that normalize all features to the same scale
Added gradientDescent.m function
Added gradientDescentMulti.m function for multivariable regression
Added normalEqn.m function
Added method, that computes sigmoid function
Added costFunction.m for logistic regression
Added costFunctionReg.m for regularized logistic regression
Added predict.m for regularized logistic regression