[MRG] 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
Please add another paragraph to analyze the obtained results, for instance:

The resulting plot shows a diagonal of strong validation scores that can be explained by the fact that for this dataset and the fixed number of hidden nodes, the overfitting introduced by setting larger random weights scales can be successfully tackled by decreasing `C` to use more regularization on the trained output weights.