the PSGI module by default now sets p6sgi instead of psgi

[krakan]

Another solution woud be to add :$psgi-classic to the populate-psgi-env call.

[AlexDaniel]

This pull request actually fixes #43

BUT!

Here:

our sub dispatch-psgi($env) {
    return dispatch($env).psgi; # <---- here
}

It seems like it has to be ｢psgi｣, not ｢p6sgi｣ like in this pull request. Otherwise it doesn't work at all.