Added sl_config.php
Merge remote-tracking branch 'upstream/master'

Conflicts:
	.gitignore
Added responsive image support

Serves responsive images based on picturefill
https://github.com/scottjehl/picturefill
Rewrites the content of a page before serving it.
This functionnality is optionnal and defined in page admin.
Added class and style attributes support
Fixed undefined index
Merge pull request #54 from lowki/master

Added responsive image support