Reduce undeeded 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 participating 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
In order to test this, first you need to apply #4868 
Then go in layouts/joomla/toolbar/confirm.php and layouts/joomla/toolbar/standard.php and comment out `JHtml::_('behavior.framework’);`. It should look like this: `//JHtml::_('behavior.framework’);`
Move around in the admin area:
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.

You should not see any error logs in your browsers developers view! If that is what you get, then you have a successful test!

Don’t forget to restore the layouts/joomla/toolbar/confirm.php and layouts/joomla/toolbar/standard.php by removing the `//`after the testing