Feature: restore including schema

[maorfr]

Currently, cain is only able to restore if a schema exists, and is in the same as the specified tag.

We could add an option to restore the schema as well, to avoid having to create the schema before restoring.

Implementation:
add a --schema string flag to restore, which will be used to specify which schema you wish to restore.

Expected behavior:
if --schema is not specified and schema does not exist - keep current behavior (error)
if --schema is not specified and schema exists and - keep current behavior (try to restore)
if --schema is specified and schema does not exist - restore schema and try to restore
if --schema is specified and schema exists and they are equal - keep current behavior (try to restore)
if --schema is specified and schema exists and they are not equal - error