Removing instead of deprecating Namespace attr
Removing instead of deprecating Namespace attr

- Per discussion, there is no reason to deal
with the complexity of backwards compatibility
with the Namespace attribute on the Restore
domain.

- Also noticed there was an error on the
validation of the BackupController where
the message would actually just be the index
of the error and not the contents of the message
itself.

Signed-off-by: Justin Nauman <2ce15d7fe08a6303460d476c892f9d66a4c967f9@gmail.com>

heptio/ark,heptio/ark