cmd2 0.7.3 started to override Cmd.completenames with a function
taking additional parameters:
Cmd2.completenames(self, text, line, begidx, endidx)
over the Cmd version:
Cmd.completenames(self, text, *ignored)
With this change we adjust the override to the new signature.
Change-Id: I7b110502c20ec16c6032cce31021eee3f85255fc
Closes-Bug: #1700250