--file for all kinds of input

[ngtuna]

Playing with Kompose, I see it would be great to use --file flag for all kinds of input format such as bundle or compose like this. We can implement a format detection prior to loading the file into corresponding package.

$ kompose --file docker-compose.yml convert
$ kompose --file docker-bundle.dsb convert

[sebgoa]

that's an interesting idea, even though I am bit weary of too much magic to detect file format...

[ngtuna]

temporarily close as --file and --bundle are now global flags.