Compiling with Godot 2.x

[gokhansolak]

I wanted to compile it with Godot 2.2 but failed since object type registration is changed with Godot 3.0. As a newcomer to Godot it was confusing. Then I found that it is already possible in the past commits.

It may be useful to update the Readme so that the people with stable version can pick it easier.

Thank you for sharing the repo.