Slide in and Fade out of tabs

[wilsonge]

Make the tabs fade/slide in and out rather than the jump to a tab as of current.

[wilsonge]

.toggle() function is currently responsible for this https://github.com/wilsonge/jjtabs/blob/master/plg_system_jjtabs/js/tabs.js#L121 and https://github.com/wilsonge/jjtabs/blob/master/plg_system_jjtabs/js/tabs.js#L124