Add compression and output file options to 'diff'
Add compression and output file options to 'diff'

Add options for writing directly to a file, and compressing the diff
stream, to the 'diff' CLI command.

Signed-off-by: Nalin Dahyabhai <f562fcb2a0b898bf0be1afc867ea92325d8f825f@redhat.com>

rhatdan/storage,containers/storage,rhatdan/storage,rhatdan/storage,containers/storage,containers/storage