accept relative paths in migrate commands

more precisely: we resolve the publish_path so it's not relative, using
realpath()

without this, relative would end up in the apache config, breaking
vhosts

migrate.hostmaster.inc

@@ -16,9 +16,7 @@ function drush_provision_hostmaster_migrate_validate($site, $platform) {
   }
 
   $data = drush_get_merged_options(); 
-  $data['root'] = $platform;
-  $data['r'] = $platform;
-  $data['publish_path'] = $platform;
+  $data['publish_path'] = $data['r'] = $data['root'] = realpath($platform);
   drush_backend_invoke('provision-verify', $data);
   // verify the current platform
   drush_backend_invoke('provision-verify', array('root' => drush_get_option(array('r', 'root'), drush_locate_root())));

web_server/provision_apache.drush.inc

@@ -26,7 +26,7 @@ function provision_apache_drush_init() {
 
     $path = drush_set_default('docroot_path', rtrim(($docroot) ? $docroot : $_SERVER['DOCUMENT_ROOT'], '/'));
     drush_set_default('sites_path', $path . '/sites');
-    drush_set_default('publish_path', drush_get_option('docroot_path'));
+    drush_set_default('publish_path', realpath(drush_get_option('docroot_path')));
 
     $parts = explode("/", $path);
     array_pop($parts);