Add NDMP vbb and image backup types.

Seems EMC uses a special type for NDMP backups named "vbb" which looks
analog to smtape and zfs we already had. Mirapoint has an "image"
backup type which also looks analog. So lets add these two types
and see how well things work out with these settings.

src/dird/ndmp_dma.c

@@ -184,6 +184,8 @@ static ndmp_backup_format_option ndmp_backup_format_options[] = {
    { (char *)"tar", true, false, true, true },
    { (char *)"smtape", false, true, false, true },
    { (char *)"zfs", false, true, false, true },
+   { (char *)"vbb", false, true, false, true },
+   { (char *)"image", false, true, false, true },
    { NULL, false, false, false }
 };
 

src/stored/ndmp_tape.c

@@ -103,6 +103,8 @@ static ndmp_backup_format_option ndmp_backup_format_options[] = {
    { (char *)"tar", false },
    { (char *)"smtape", true },
    { (char *)"zfs", true },
+   { (char *)"vbb", true },
+   { (char *)"image", true },
    { NULL, false }
 };