docs: Update README and CHANGELOG

Added CHANGELOG entries for the changes since Puppetboard 0.0.2.
Done some serious work on the README which now includes much improved
and tested installation instructions.

CHANGELOG.rst

@@ -2,6 +2,42 @@
 Changelog
 #########
 
+This is the changelog for Puppetboard.
+
+0.0.3
+=====
+This release introduces a few big changes. The most obvious one is the
+revamped Overview page which has received significant love. Most of the work
+was done by Julius Härtl. The Nodes tab has been given a slight face-lift
+too.
+
+Other changes:
+
+* This release depends on the new pypuppetdb 0.1.0. Because of this the SSL
+  configuration options have been changed:
+
+  * ``PUPPETDB_SSL`` is gone and replaced by ``PUPPETDB_SSL_VERIFY`` which
+    now defaults to ``True``. This only affects connections to PuppetDB that
+    happen over SSL.
+  * SSL is automatically enabled if both ``PUPPETDB_CERT`` and
+    ``PUPPETDB_KEY`` are provided.
+
+* Display of deeply nested metrics and query results have been fixed.
+* Average resources per node metric is now displayed as a natural number.
+* A link back to the node has been added to the reports.
+* A few issues with reports have been fixed.
+* A new setting called ``UNRESPONSIVE_HOURS`` has been added which denotes
+  the amount of hours after which Puppetboard will display the node as
+  unreported if it hasn't checked in. We default to ``2`` hours.
+* The event message can now be viewed by clicking on the event.
+
+Puppetboard is now neatly packaged up and available on PyPi. This should
+significantly help reduce the convoluted installation instructions people had
+to follow.
+
+Updated installation instructions have been added on how to install from PyPi
+and how to configure your HTTPD.
+
 0.0.2
 =====
 In this release we've introduced a few new things. First of all we now require