rename wp-migrate-db to wp-sync-db

add in a short explanation as to why it's renamed
rewrite a bunch of the readme
remove sass

it was removed from the distribution, and I don't really like sass much
anyway
reformat CSS
update css to v1.4
remove media files addon icon

not needed because we don't have an addons/upsell tab
reformat code
update js to 1.4b
upgrade to 1.4b