fix sphinx version lookup problem due to versioneer switch

Author: wholmgren

docs/sphinx/source/conf.py

@@ -77,16 +77,13 @@ def __getattr__(cls, name):
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
-# Get the version from the version file
-version_file = os.path.join(os.path.dirname(__file__),
-                            '../../../pvlib/version.py')
-with open(version_file, 'r') as f:
-    exec(f.read())
+
+import pvlib
 
 # The short X.Y version.
-version = __version__
+version = '%s' % (pvlib.__version__)
 # The full version, including alpha/beta/rc tags.
-release = __version__
+release = version
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.