Correct author to oemof developER group

Author: SabineHaas

setup.py

@@ -10,7 +10,7 @@ def read(fname):
       version='0.1.2dev',
       description='Creating time series of wind power plants.',
       url='http://github.com/wind-python/windpowerlib',
-      author='oemof developing group',
+      author='oemof developer group',
       author_email='windpowerlib@rl-institut.de',
       license=None,
       packages=['windpowerlib'],