NX subscribe_xpath API fix

Client super class expecting a prefix proto.Path parameter not passed in by NX subclass.

v1.0.13

Re-release from tag. Decorates XPath to gNMI methods as classmethod for simpler usage. Adds Subscribe request Mode to CLI.

v1.0.11

Adds Get/Set/convenience functions for NX-OS, as well as prefix arguments.

v1.0.10

Exposes gRPC channel in Client and ClientBuilder.

v1.0.9

Add insecure connectivity support. This is not recommended for usage.

v1.0.8

Adds better logging and fixes Set prefix handling.

v1.0.7

Adds several examples, and new aliases for Client/OS wrappers.

v1.0.6

Adds subscribe_xpaths to the base Client class and includes various fixes and improvements regarding certificate generation, etc.

v1.0.5

Adds cisco-gnmi command upon installation via cli.py.

v1.0.4

Adds IOS XR CLI functionality.
XRClient.get_cli thanks to @cprecup.