Added a custom package to inject datetime in templates

Modified blog pagination filter to show only posts which pubdate is
less or equal than today's date.

packages/template-datetime/setup.py

@@ -0,0 +1,15 @@
+from setuptools import setup
+
+setup(
+    name='lektor-template-datetime',
+    version='0.1',
+    author=u'Felipe Martin',
+    author_email='me@fmartingr.com',
+    license='MIT',
+    py_modules=['lektor_template_datetime'],
+    entry_points={
+        'lektor.plugins': [
+            'template-datetime = lektor_template_datetime:TemplateDatetimePlugin',
+        ]
+    }
+)