flask_sqlalchemy example : different types with the same name in the schema: EmployeeConnection, EmployeeConnection.

Hi,

I followed the instruction to use the flask_sqlalchemy example with a Python 2.7 version, when I run the app.py script, I've got the following error :

```
(py27) λ python app.py
Traceback (most recent call last):
File "app.py", line 7, in
from schema import schema
File "D:\Thomas\Dev\graphene-sqlalchemy\examples\flask_sqlalchemy\schema.py", line 60, in
schema = graphene.Schema(query=Query, types=[Department, Employee, Role])

....

File "D:\Programmes\Anaconda2\envs\py27\lib\site-packages\graphene\types\typemap.py", line 99, in graphene_reducer
).format(_type.graphene_type, type)
AssertionError: Found different types with the same name in the schema: EmployeeConnection, EmployeeConnection.
```

What am I doing wrong ?

Thank you

Reproduza a falha executando examples/flask_sqlalchemy/app.py com a configuração do Python 2.7 descrita e, em seguida, inspecione schema.py nas proximidades da linha 60, onde o esquema do Graphene é criado. Rastreie por que EmployeeConnection é registrado duas vezes e confirme que o exemplo é iniciado sem a assertion.

Escrita pelo modelo de indexação a partir do texto da issue.