Merge pull request #171 from cabrera/pypy_no_warn_cython

fix(setup): don't warn re: cython under pypy

Fixes issue #167

setup.py

@@ -10,17 +10,23 @@ REQUIRES = ['six']
 if sys.version_info < (2, 7):
     REQUIRES.append('ordereddict')
 
-#if 'develop' not in sys.argv
-
+PYPY = True
+CYTHON = False
 try:
-    from Cython.Distutils import build_ext
-    with_cython = True
-except ImportError:
-    print('\nWARNING: Cython not installed. '
-          'Falcon modules WILL NOT be compiled with Cython.\n')
-    with_cython = False
+    sys.pypy_version_info
+except AttributeError:
+    PYPY = False
 
-if with_cython:
+if not PYPY:
+    try:
+        from Cython.Distutils import build_ext
+        CYTHON = True
+    except ImportError:
+        print('\nWARNING: Cython not installed. '
+              'Falcon modules WILL NOT be compiled with Cython.\n')
+        CYTHON = False
+
+if CYTHON:
     ext_names = (
         'api',
         'api_helpers',