[COOK-4368] - Improve documentation to include all attributes

Signed-off-by: Sean OMeara <someara@opscode.com>
Version bump to 0.9.12
Publish 0.9.12 Changelog
Version bump to 0.9.13 (for development)
RHEL support
Support Varnish 4.0
Some cleanup
Merge pull request #20 from ameir/rhel+cleanup

Some modern cookbook updates
Make VCL generation optional

fixes #17
thanks to davel (github) for this
Merge pull request #22 from rackspace-cookbooks/pr-17

Make VCL generation optional
Add support for extra parameters

Thanks to sebastianrodriguez for the support in #13
I didn't take in the thread_pool_min/max since it's redundant

fixes #13
Merge pull request #23 from rackspace-cookbooks/pr-13

Add support for extra parameters
fixing rubocop and foodcritic errors
Merge pull request #24 from rackspace-cookbooks/rubocop

fixing rubocop and foodcritic errors
Adding compatibility for ubuntu 12.04 and centos 6.5 (tested with version 4.0)
Adding centos-default.erb
modified config location logic to always set a value
allow template to work on centos
Merge branch 'compatibility' of github.com:rackspace-cookbooks/varnish into compatibility
updating readme and removing unneeded templates
updating metadata
the system config file actually works now