Reduce unneeded calls for mootools

#### Executive summary
Lately Joomla made some shift from mootools to jquery, for a number of scripts, thanks to the work of people participated on Joomla! Google Summer of Code Program in 2013. Although we use, let’s say, form validation in conjunction with jquery we still do call mootools as well. Which is wrong, as we increase the http requests without any benefits! So this PR tries to bring some sanity to what framework is loaded, by:
1 Removing uneeded calls for mt in cms/html/behavior.php
2 Corrects the multiselect.js script (and the uncompressed) to remove an error (Joomla is undefined)
3 Correct the view of administrator/com_users/views/mail/tmpl/default.php (chosen is called but not core.js)
4 Move all the calls from toolbar buttons to their respective layouts

#### Testing

### UPDATE PLEASE SEE THE TESTING INSTRUCTION ON THE PRs 
`Introduce jquery formvalidator for com_xxxxx`
BUT ALSO CHECK THESE:

administrator/index.php?option=com_checkin should demonstrate multiselect without mt
administrator/index.php?option=com_users&view=mail should demonstrate form sent and validate without mt
administrator/index.php?option=com_modules should demonstrate multiselect and combobox without mt
http://localhost/administrator/index.php?option=com_admin&view=sysinfo should demonstrate highlighter.js without mt
Logout and log in to demonstrate the use of noframes without mt.