spek-41 init keyword is clunky

[paslavsky]

I added constructor to the Spek class with optional parameter that allow to create tests with the following syntax:

class SomeTest: Spek({
    give("...") {
        ...
    }
})

This parameter is optional so the backward compatibility is stored

[hhariri]

We've substantially modified the structure and fixed some of the things moving forward. The changes will be in the 1.0 branch which will be for the release.