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
+1 for renaming this to `_predict` and defining:

```python
class ELMClassifier(...):
    ...
    def decision_function(self, X):
        return self._predict(X)
```

and:

```python
class ELMRegressor(...):
    ...
    def predict(self, X):
        return self._predict(X)
```