Async ajax calls for some visualisations

If the dashboard contains lots of widgets/visualisations the UI get's quite slow. 2-3 seconds for a few widgets.

This change makes the rawdata and realtime widget to use a new async function instead which doesn't block the javascript thread in the browser - this makes the dashboard feel alot snappier and page load is about 0.5sec instead in comparsion on my test. All widgets get visualised meanwhile the data is loading, then updated. 

Also the widgets does not freeze during data-load anymore (for example zooming and time range change).

There is also some jquery optimisations where the DOM-node is cached/lookuped once instead of lookedup several times every update.

+Some html-markup errors fixed.