prevent pipeline from dying on Closure Compiler warnings

Coffeescript compiler now accepts .litcoffee and .coffee files.

fixed issue #271

Update using.rst

we started to use django-pipeline in Borsala production servers.

Fix Python 3 compatibility

Python 3 compatibility has been lost. Readd it.

finders.py: use chain to concatenate dictionaries instead of + operator.
glob.py: use list compresension instead of filter and lambda.
utils.py: use urllib.parse.quote instead urllib.quote if available.

Remove unneeded unittest2 dep.

Documenting the default JS template behavior w/ extra_context

Support for the async and defer tag attributes is not documented and requires examining the source.

Include documentation sources in PyPi releases.

It is not used anywhere.

MinifyHTMLMiddleware should rely on PIPELINE_ENABLED, not DEBUG

Compiler was writing new content to files on paths that wasn't findable by the compressor. Fixes #228

Recalculate content-length

Added tests to make sure when a response is compressed the 'Content-Length' header is included in the response, otherwise the client (curl for example) will be confused about the content length

It is needed according to
https://github.com/django/django/blob/master/django/middleware/gzip.py#L46

Make sure the prefix and first part of name are equivalent. close #226