Edit Assetstores

Added the ability to edit assetstores.  If the assetstore has any files, a warning is shown and the save button has the warning icon on it.  As part of this, added the backend ability to edit S3 assetstores.  Added tests for editing assetstores.

Removed ALL timed waits from the web client tests (unless there are some in the plugins).  Before, we often were not waiting for the dialog backdrop to vanish, instead some times deleting it.

Clear the filesystem assetstore from disk before running a test.  If you ran repeated tests, this was using up a small amount of disk space.
For the above two lines, let's use `_.each` and `_.has` rather than `for..in` and `hasOwnProperty`.