Refactor persistence to an storage class.
Add aws parameters to configuration.
Fix small bug in after test cleaning.
Add S3 storage.
Merge branch 'master' into s3storage

Conflicts:
	lib/imprenta.rb
	lib/imprenta/cache_page.rb
	lib/imprenta/storage/file.rb
Refactor: Rename some classes. Better code organization.
Add naive content server for s3.
Add max age to response.
Merge branch 'master' into s3storage
Update README.md

Add docs for S3 settings and configuration.
Update README.md
Merge pull request #3 from skyscrpr/s3storage

S3storage