Added typescript definitions

[nathanlepori]

All typing should be mostly correct. Uses module augmentation to add .guard member. Custom user model class can be augmented using empty interface like so:

interface User extends GuardUser {}
class User extends Model {
    ...
}

[pankajvaghela]

Thanks for the PR @nathanlepori . and sorry for such a late reply...

I will look into it as soon as possible. currently I'm bit busy with some school stuff so might take some time.

[nathanlepori]

No problem take your time. Thanks for looking into this