Fix the resolution width for retina images
Add `image_attributes` and `image_attachment_data` to the breakpoint filter.
Add `image_size` to the resolution filter.
Update examples to reflect update to the breakpoint filter
Update version number
Clear the Picturefill.WP transient cache on update.
Update the version after the update action is called.
Rename `clear_picturefill_wp_cache` method to `clear_picturefill_transients` and add a similar method to clear all Picturefill.WP options on deactivation.
initiate plugin on `plugins_loaded` hook
on the off chance anyone wants to do any advanced hacking.
Check for `ABSPATH` to protect global variables