The jquery version is upgraded to 1.9.1

* This should solve the issue #155 and similar browser-related issues.
* The jquery-migrate plugin is also added and included on a page to fix any interoperability issues.
* The two versions - source and minified is provided for each js-file involved.
* Commented out lines are added to the `configuration.inc.php.sample` file to use source or minified version.
* The hard-coded jquery version is cleaned up from the `assets/_core/php/profile.php` script.