igLoading should be made part of the themes

[kdinev]

Currently the loading indicator is a gif, which is not a very modern approach. We should move the igLoading to be a CSS component and the different themes should provide different look and feel for the loading indicator.

[StefanIvanov]

We should consider the following properties:

• [ ] Delay - in seconds that upon timing out triggers the showing of the loading indication
• [ ] Progress in % - possible to show if we have an estimation for the expected completion, when loading indication is hidden
• [ ] Overlay - background for the loading indication allowing to darken/brighten the content under it
• [ ] Types/Animations - we should support a few different visualizations for the loading indication
• Spinning balls
• Spinning bars
• Azure rings
• Gears
• [ ] Rotation direction for the spinning loading indication that is clockwise (default) and counterclockwise
• [ ] Size of the spinning indication - width and height
• [ ] Color fill selection and theming of the loading indication
• [ ] Text for the loading indication and properties for that text e.g. "Loading data" "Connecting to server"

We should consider the following methods:

• [ ] Show and hide the loading indication which implicitly starts/stops the accompanying animations immediately or after a delay
• [ ] Setting and changing the text for the loading indication