1) Enhanced REST server to parse URL query parameters and pass them to
translib APIs. Handles RESTCONF "depth" and a custom "deleteEmptyEntry"
query parameters. The deleteEmptyEntry parameter is valid only for
DELETE requests; takes a boolean value - "true" or "false". It will be
passed to translib via SetRequest.DeleteEmptyEntry property. App modules
and transofrmer changes to handle these parameters is pending.

2) Modified cli_client get() and head() python APIs to accept optional
depth parameter, which should be a +ve integer. By default no depth
value is passed to the server. Usage:
    cl.get(path, depth=2)
    cl.head(path, depth=1)

3) Modified cli_client.delete python API to accept an optional
deleteEmptyEntry parameter. Default value is False. When specified as
True, the DELETE request will include "deleteEmptyEntry=true" query
parameter. Usage:
    cl.delete(path, deleteEmptyEntry=True)