Curried compose and pipe + partially function

Solution to #135

`compose` and `pipe` now return a partially applied function when they are called with only one argument, for this they use the function `partially`.

`partially (f, a)` is a function that return the partial application of `a` to `f` (although this could later be generalized for *n* arguments `a, b, c...`). `partially` is useful for variadic functions because they can't be curried.

Code snippet of compose
```
var f = arguments[0];
if (arguments.length == 1) {
    return partially (compose, f);
}
```