Use DefinitelyTyped backbone typings

[postatum]

Fixes #26

I've used backbone typings from https://github.com/DefinitelyTyped/DefinitelyTyped because after installing them this way it tsc works fine.

Also removed typings for:

• jquery, because DefinitelyTyped installs it as dependency of backbone
• globals/modules jointjs because it's already defined by the library

I didn't use DefinitelyTyped for all typings because not all of them are available there so I thought we use DefinitelyTyped for one particular case of backbone and typings/typings for the rest.

[antoniogarrote]

Using the alternative fix in #30 Closing this PR.