setup.py: zeroconf and netifaces are optional dependencies

Move them to extras_require.

setup.py

@@ -40,9 +40,6 @@ def get_data_files():
 
 def get_requires():
     requires = ['psutil>=2.0.0']
-    if sys.platform.startswith('linux') or sys.platform.startswith('darwin'):
-        requires += ['zeroconf>=0.16']
-        requires += ['netifaces']
     if sys.platform.startswith('win'):
         requires += ['colorconsole']
     if sys.version_info < (2, 7):
@@ -67,7 +64,8 @@ setup(
         'SENSORS': ['py3sensors'],
         'BATINFO': ['batinfo'],
         'SNMP': ['pysnmp'],
-        'CHART': ['matplotlib']
+        'CHART': ['matplotlib'],
+        'BROWSER': ['zeroconf>=0.16', 'netifaces']
     },
     packages=['glances'],
     include_package_data=True,