First cache impl

Empty charmbrowser container on destroy

Test added.
Remove crufty double click handler.
Comments per review.
Additional comment per review.
Merge pull request #355 from makyo/curated-cache

This is a first iteration of caching charmbrowser requests.

To QA, with il flag:
* deploy a service
* closer the inspector; interesting should load immediately
* search for apache
* deploy a service
* close the inspector; apache search results should load imeediately.
Fixed sidebar header capitalisation.
Merge pull request #358 from huwshimi/uppercase-headings

Part of @hatched's refactoring left the headers with lower case titles, this branch fixes that with CSS.
Merge pull request #357 from kadams54/service-dblclick

Full confession: I didn't actually do anything to fix the inspector breakage. I was able to duplicate the bug a few times initially and then unable to duplicate once I started working on it. The destructor in `viewlet-manager.js` should handle removing the DOM node, which is what I thought the original problem was.

Instead I ended up removing the double click event, since there's no longer any difference between clicking once and clicking twice.

## QA

With the `il` flag.

1. Drag a charm to the canvas
2. Deploy it
3. Double click on the service icon
4. Close the inspector

Ensure the sidebar does not break and reverts back to the charmbrowser as expected. You can also inspect the DOM and make sure `<div class="bws-content">` has only one child.