Remove need for header clients to pluralize.
Update machine headers on add/remove.
Merge pull request #346 from kadams54/fix-mv-headers

### QA

1) With the `/:flags:/il/mv` active, switch to the machine view.
2) Deploy a bundle.
3) Ensure the machine column count is updated properly. Note that there's a known bug where the same machine will be rendered multiple times to the column, which has its own card. Nonetheless, the header should maintain the correct count.
4) Select a machine and make sure the container/unit header updates properly.

This branch fixes both the "Fix machine count…" and "Investigate using handlebars pluralize…" cards.
Destroy old inspectors when changing state.
Merge pull request #349 from makyo/duplicate-buttons

QA with il flag - deploy two services, then click each in turn.  There should be no lingering expose toggle from the previous inspector.
Moved the search widget instantiaion and rendering into the charmbrowser view
Made loading indicator render in the proper place
Created search widget management extension to be mixed into the charmbrowser view
Search widget now functions properly being 100% rendered and managed in charmbrowser view