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
No :-), 
the updated code does this, 
```python
batches = gen_batches(n_samples, batch_size)
# Extract first batch
batch_slice = batches.__next__()
```
I am not sure if `__next__()` is appropriate.
Thanks.