Add SVM to RegERM framework

First approach to solve SVMs in a general framework.
- add README, REQUIRE, and Makefile
- add first attempt to solve svms using standard optimizer (lbfgs)
- add tests
Add logistic regression and refactoring

- add logistic regression
- extract regularizer and loss functions; renaming
- add other loss functions and regularizer
- move regularizer parameter to initialization
Add Travis

- add .travis.yml
- adapt README.md