Fix some type error bugs

[Cantoria]

basestring --> str
float -->int

[machao199271]

Hi bro,

I try to run the old demo the day before yesterday. Cascade forest worked, but fine-gained didn't.
Then I modify the code yesterday, very similar with yours, but change two more arguments from float to int. It run, but very bad accuracy.
This morning, I saw your pull, and try it on the demo, it run and got good accuracy.

It's so lucky for me to see your pull today.

@kingfengji, hope you can approve this pull.

Ma Chao

[932179209]

@Cantoria Hi!
I'm using Python3 to run the code and meet the same problem. Although it's a small problem, I have to say It's A Very useful Pull to solve it, especially for the beginner!

BTW, the "basestring" problem can also be solved by changing it with six.string_types (@kingfengji has share this method in one of the closed issues, and remenber to import six)

It seems like this gcForest code is not updating anymore, BUT I came here because yours new paper-"Multi-Label Learning with Deep Forest", and it's turely inspiring. The article just mentioned the gcForest's code can be found here, and the one who wants to follow the work may confused about the problem.

So I sincerely hope @kingfengji can approve this pull and update the code regularly from your busy work!