Fix incorrect settings names in usage docs

The start of the usage docs referred to the old 'CUMULUS_API_KEY' and 'CUMULUS_CONTAINER' settings.
One more old reference (to 'CUMULUS_FILTER_LIST') was found in the syncstatic command section.
Merge pull request #56 from SmileyChris/patch-1

Fix incorrect settings names in usage docs
Added note about move to django-storages
Update README.rst
Expose SSL to context processor

This enables the developer to selectively use the secure URL. Currently
the setting is site-wide and this is fine for images but Chrome expects
to get CSS from a secure URL if the page itself is served from one.
Expose URLs to static CloudFiles storage to templates

This context processor allows drop-in replacement of local static
files with a CloudFiles CDN storage. The SSL URL is also provided
as a context variable in case it is explicitly required. In case
some files are stored locally in the STATIC_URL, it can be accessed
through the LOCAL_STATIC_URL context variable.
fixed bug that doesnt work on all python versions on different OSes
Allow container name to be overridden at runtime
Allow importing the cumulus module without configuring it
Added support for setting a custom TTL on the container
Make sure the TTL is also set on the container if it is already public
Resurrected bendavis78's modified_time support to aid with collectstatic
Add an error message and some air between the lines

The NotImplementedError may be confusing without a due explanation.
Also added some newlines to make the method a little more readable.
Add support for custom headers based on a regex pattern
Document functionality from @tgecho

Added explanation to the HEADERS setting.

Caveat: Chrome will still whine on the console about mime types if
the uploading system does not define them correctly for fonts. This
applies if collectstatic is executed from Heroku.
Custom headers: allow multiple matched patterns and apply all matched headers
Added gzip compression support
Use newer python-cloudfiles

The newer version allows setting headers hence there is no longer
a need to check for the existence of the headers property.
added the CONTAINER_URI settings: if specified, we don't need to query cloudfiles to resolve every file URL.
Merge pull request #65 from ferrix/pull_queue

Tested and prepared combined pull requests