Added .scalar to Queryset

More efficient than the previous .values_list implementation Ref #393
Reverted some of the .values_list code thats no longer needed.

Closes #415

setup.py

@@ -38,7 +38,9 @@ setup(name='mongoengine',
       packages=find_packages(),
       author='Harry Marr',
       author_email='harry.marr@{nospam}gmail.com',
-      url='http://hmarr.com/mongoengine/',
+      maintainer="Ross Lawley",
+      maintainer_email="ross.lawley@gmail.com",
+      url='http://mongoengine.org/',
       license='MIT',
       include_package_data=True,
       description=DESCRIPTION,