Update hierarchical tests to use dstore/Tree
createHierarchicalStore: Fix top-level filter

Use getRootCollection, but redefine it to work with our test data
Use dstore/Tree in more tests

* Fix IDs in rest.php and convert strings to use single quotes
* Use dstore/Tree in Rest.html
* Use dstore/Tree in Tree-expand-promise unit tests
createAsyncStore: Remove obsolete TODO