Add xpath suppot for FormRequest.from_response.
Removing plural from httpcache stats' value names.
Add middleware support for real HTTP caching. Add httpcache setting to allow either real or dummy HTTP caching (for backwards compatibility it's set to use dummy cache by default).
Add middleware support for the 'no-store' Cache-Control directive.
Add cache storage support for real HTTP caching. Add real HTTP caching unit tests for both middleware and cache storage.
Updated the downloader middleware documentation to reflect changes introduced by the support for real HTTP caching.
Implemented policies for HTTP Cache
Remove plural from stat key.
Implement single HTTP cache policy
Merge branch 'master' of git://github.com/scrapy/scrapy into http-cache-middleware
Instead of extending from HttpCachePolicy, following the same approach used for storage selection
Fixed typo

'persitent' --> 'persistent'
Merge pull request #215 from kuyan/patch-1

Fixed typo
Added --spider option to "shell" command.
lint and improve images pipeline error logging
Merge pull request #216 from Mimino666/shell-spider-option

Added --spider option to "shell" command.
Fixed error message formatting.
log.err() doesn't support cool formatting and when error occured, the message was:
	"ERROR: Error processing %(item)s"
Added model validation to DjangoItem.
Added "exclude" parameter testing to unittests.
Merge pull request #217 from Mimino666/item-processing-errormsg

Fixed error message formatting.