cli: add -u parameter for REST URI
cli: add -u parameter for REST URI

The -u parameter accepts a REST URI string argument. The URI argument
can currently only specify the protocol/provider type (Amazon S3 or
Azure Block Blob).
In future it will allow override of the default REST server host.

Signed-off-by: David Disseldorp <589a549dc9f982d9f46aeeb82a09ab6d87ccf1d8@suse.de>

ddiss/elasto,ddiss/elasto