swift-mock: test isolation between tests

We want individual it-blocks to begin with a fresh state. This is
actually ensured by the call to browser.get, which is what triggers a
page load and makes Protractor load the mock modules.
swift-simulator: extract accountUrl function
swift-simulator: extract regexp escape function
swift-simulator: handle non-existing containers

The connnect static server we use for testing return a 500 error for a
GET request to a path like 'index.html/foobar'. We now catch these and
return 404 like the real Swift does.
swift-simulator: handle listObjects with no query string

Before, the listObjects call failed when it tried to access
params.prefix.length. We now default prefix to ''. Further, delimiter
defaults null, which works with indexOf(params.delimiter).

This is now tested with a dedicated test.
swift-simulator: test deleteObject returning 204
swift-simulator: test deleteObject returning 404
swift-simulator: test deleteObject with non-existing container
Merge pull request #72 from mgeisler/test-swift-mock

Test SwiftSimulator