Completion and usage message output should use name of invoked command, not "hassio-cli"

[scop]

As discussed in #138, when one issues the completion command to output bash completion, the output is always applied to the command name hassio-cli. This is a problem if the command is installed under a different name, e.g. hassio.

The same problem seems to be in a lot of other places as well, for example usage messages say hassio-cli no matter what the executable's filename is.

The fix would be to use the invoked command's name in usage messages and bash completion output etc.