updating to reflect the new name + URL

Author: perimosocordiae

setup.py

@@ -3,12 +3,12 @@
 from setuptools import setup
 
 version = "0.1.0"
-setup(name='metric_learn',
+setup(name='metric-learn',
       version=version,
       description='Python implementations of metric learning algorithms',
       author=['CJ Carey', 'Yuan Tang'],
       author_email='ccarey@cs.umass.edu',
-      url='http://github.com/all-umass/metric_learn',
+      url='http://github.com/all-umass/metric-learn',
       license='MIT',
       classifiers=[
           'Development Status :: 4 - Beta',