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
Would this work?
```python
inplace_activation = ACTIVATIONS[self.activation]
inplace_activation(hidden_activations)
```
or is it preferable to still write it this way?
```python
hidden_activation = activation(hidden_activations)
```
do you know whether adding `hidden_activation =` involves an extra copy of the matrix?