Add action hooks
Add filter hooks
A few more actions and filters
re: issue #8
Add a template_data filter for each template file.
Add a list of hooks
re: issue #9
Add caching to the `the_content` filter.
remove any cached data on deactivation.
re: issue #12
also rename `picturefill_scripts` to `register_picturefill_scripts`
Wait on adding empty actions until I can think of a use case for them.
re: issue #8
Remove actions from  documentation.
Update picturefill.js to reflect recent changes made to @scottjehl's original.
re: issue #14
Images will now append to the matched span, allowing for greater styling control.
Move image attachment data filter to model
Separate out caching to its own method.
Correct attachment id error
Add a filter to change cache duration
Add plugin update hook
correct image attachment data filter
Move image sizes filter to model
Improve regex matching
Add examples re: issue #10
Add actions before and after the images are replaced
Update version numbers