Tries to fix RTD compilation error

http://stackoverflow.com/questions/32729978/read-the-docs-build-failing-without-errors

setup.py

@@ -23,9 +23,6 @@
     long_description = long_description,
     url='http://www.uni-kassel.de/go/pandapower',
     license='BSD',
-    install_requires=["pypower>=5.0.1",
-                      "pandas>=0.17.0",
-                      "networkx"],
     packages=find_packages(),
     include_package_data=True,
     classifiers=[
@@ -45,4 +42,4 @@
         'Programming Language :: Python :: 3.5',
         'Topic :: Scientific/Engineering',
     ],
-)
+)