Improvements to both bookmarlet and CMS

Multiple bug fixes / enhancements made to the bookmarklet and CMS:
* Progress bar now displays on first execute
* Now checks against server for latest version of files
  * Informs the user if out of date with call to action
* CMS now performs multiple uploads at the same time
* CMS not automatically resizes images that are uploaded
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* Refactored some commonly used PHP files - moving them to the /lib folder for easier maintainability

Signed-off-by: Matt Rayner <matt@mattrayner.co.uk>