Added a background over the gui behind the deployer confirm. Fixed sidebar details panel height.
Merge pull request #307 from huwshimi/mv-polish

1. Added a background over the gui behind the deployer confirm as per designs here: https://drive.google.com/a/canonical.com/folderview?id=0B7XG_QBXNwY1WGlyVzN2LWtrcmM&usp=drive_web

Most of the changes are indentation due to adding a wrapping `bar` element.

QA: Click deploy in the deployer bar and the visible area of the gui behind the changes panel should be covered in a semi transparent black.

2. Fixed sidebar details panel height (it wasn't quite touching the top).

QA: Click on a charm or bundle in the sidebar. The details panel should sit nicely below the environment header.