GSoC 2014: Standard Extreme Learning Machines

Finished implementing the standard extreme learning machines (ELMs). I am getting the following results with 550 hidden neurons against the digits datasets,

Training accuracy using the logistic activation function: 0.999444
Training accuracy using the tanh activation function: 1.000000

Fortunately, this algorithm is much easier to implement and debug than multi-layer perceptron :).
I will push a test file soon.

@ogrisel , @larsmans
```
    class_weight : dict, 'auto' or None
        If 'auto', class weights will be given inverse proportional
        to the frequency of the class in the data.
        If a dictionary is given, keys are classes and values
        are corresponding class weights.
        If None is given, the class weights will be uniform.
```