Defer fetching updates until first render; first step towards new update ux

Move upgrade-charm to be its own viewlet; unstyled first iteration

Make prep.
Added explicit labels to the keyboard shortcuts.
Added a keyboard shortcut to show and hide the sidebar.
Only allow one unit token to be in placement mode.
Tests rearranged to reflect new viewlet.
Merge pull request #404 from huwshimi/single-place

Only allow one unit token to be in placement mode

To prevent the list of machines and containers getting outdated by starting the move form on multiple unit tokens this branch makes it so you can only show the form on once token at once.

See: https://bugs.launchpad.net/juju-gui/+bug/1329224

QA:
- drag several charms to the canvas
- open the machine view
- click the 'move to' icon on one of the tokens
- now click on a different 'move to' icon
- the second token should now display the placement form and the first token should be reset to its initial state
- subsequent clicks on 'move to' icons should continue to only display the form on the last clicked token
Merge pull request #405 from makyo/cw-calls

Move update charm to new UX - first iteration

This branch moves the update charm functionality out of the service overview viewlet and into its own viewlet that can be loaded on demand, rather than on opening the inspector.  Note that there are follow-up style branches, and may be follow-up technical branches as well - first iteration.
Merge pull request #403 from huwshimi/hide-sidebar-shortcut

Hide sidebar shortcut

This allows you to hide the sidebar with Ctrl+Alt+h.

I also did a drive-by in the shortcuts panel to expand all the shortcuts to display "Alt" instead of "A" etc.