Fix requirements.

Author: ggventurini

setup.py

@@ -18,7 +18,7 @@ def read(fname):
     package_data={
       'deltasigma': ['test_data/*.mat', 'test_data/*.txt']
     },
-    install_requires=['numpy>=1.8.0', 'scipy>=0.11.0', 'matplotlib>=1.1.1'],
+    install_requires=['numpy', 'scipy>=0.11.0', 'matplotlib>=1.1.1'],
     zip_safe=False,
     include_package_data=True,
     author="Giuseppe Venturini and others",