Added Custom Bootstrap Theme Support

I have added Custom Theme Support. Theme should be in "webroot.theme" directory.
Setting in config/main.php would be:
 
'bootstrap' => array(
            'class' => 'bootstrap.components.Bootstrap',
            'customTheme'=>true,
            'customThemeName'=>'bootstrap.min.cosmo.css',
            'yiiCss' => false
)

yiiCss needs to be false to work, if true it will not register the Bootstrap Theme.