JWT auth uses a non-standard parameter name for mount_point

[briantist]

Related: #644

The JWT auth method class uses the parameter path for the mount point in all of its methods , which strays from every other auth method which uses the name mount_point.

I think it should be consistent with the other methods.

Since it's already published as is, perhaps adding mount_point as a parameter with the same purpose and deprecating path to be removed in a future release (having both for some time) is a good path forward?