Fix a number of marketplace issues:
* Minor CSS change to not vertically align images to the middle.  Whole UX needs a load of help.
* Remove the extract() call to the args var.  Wasn't doing anything besides throwing a notice.
* Add user agent string to Auth requests.  Necessary with new server mod_sec rules.
Merge branch 'master' of https://github.com/wp-e-commerce/WP-e-Commerce