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

Don't install "tests.tests" package

ensure file globing is deterministic

A small change to ensure the order of filenames returned from glob() is deterministic. This is required to provide consistant file order (and therefore minified file version hashs) when running collectstatic on multiple servers.

packaging fix for tests

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

Also picks up some missing files in tests/assets and tests/assets2

normalize paths in match_location