Don't raise an error if BeautifulSoup isn't installed
Make CssCompressor class easier to extend

Avoids the need to override split_content in subclasses of CssCompressor
changed DEBUG_TOGGLE from 'None' to None
fix tests for DEBUG_TOGGLE
+ add rcssmin
Fix windows line endings in offline compress

django itself always opens template files in binary mode, which causes an issue with offline compression on windows when template files contain windows line endings.
* changes for pass flake8
Configure tox and requirements to test with django 1.6
Support for the kind in the endblock

Example:
{% block css %}
... some other stuff
{% endblock css %}

Instead of (both are supported):
{% block css %}
... some other stuff
{% endblock %}
added additional tests
Allow data-uri filter to handle external/protocol-relative references
Fix for extracting version number in Python 3

setuptools chokes when installing a tarball of django-compressor's
HEAD of develop under Python 3. The flaw lies with extracting the
version number.

As suggested by @jezdez, this commit merely ports the version
extracting code from django-configurations.
Bump version number to 1.4a1

As 1.3 has been released, the version number should be bumped.
Merge pull request #463 from maikhoepfel/fix/setuppy

Fix for extracting version number in Python 3
Merge pull request #451 from diox/tox-add-django-1.6

Configure tox and requirements to test with django 1.6
Merge pull request #427 from jor123/patch-1

Make CssCompressor class easier to extend
Use tox also on Travis to normalize test environment.
Fix typo.
Updated URL.
Merge pull request #453 from WoLpH/develop

Support for the kind in the endblock