Bug on application CLI main

[shayaniox]

Running the applications without any parameters will result:

Traceback (most recent call last):
  File "/home/shayan/.virtualenvs/dolphin/bin/dolphin", line 11, in <module>
    load_entry_point('dolphin', 'console_scripts', 'dolphin')()
  File "/home/shayan/workspace/restfulpy/restfulpy/cli/launchers.py", line 20, in __call__
    return self.launch()
  File "/home/shayan/workspace/restfulpy/restfulpy/application/cli/main.py", line 72, in launch
    sys.exit(exitcode or 0)
UnboundLocalError: local variable 'exitcode' referenced before assignment

because the exitcode variable doesn't have a primary value:

https://github.com/Carrene/restfulpy/blob/56da177a1d9bfd980241e80b64d2f1f7949830b4/restfulpy/application/cli/main.py#L68