Change to state classes rather than adding hidden class.
Merge pull request #423 from huwshimi/state-classes

Change to state classes rather than adding hidden class

Instead of adding the `hidden` class to show the correct parts of the UI, this branch tracks the state on the container, allowing the UI to be set correctly through CSS.

QA: Try placing units and creating containers and machines and check that the appropriate bits of UI are shown.
Select the first machine and bare metal container by default.
Merge pull request #424 from huwshimi/default-selected-machine

Select the first machine and bare metal container by default.

This branch selects the first machine by default when the machine view panel is opened. Additionally, when you select a machine the bare metal container is now selected by default.

QA:
- drag two charms to the canvas
- click deploy and confirm
- open the machine view panel
- the first machine should be selected and the bare metal container should be selected
- click on the unselected machine
- the containers for the second machine should be shown with the bare metal container selected