add --offline option to run-tests command

Author: remicollet

run-tests.php

@@ -632,6 +632,9 @@ function save_or_mail_results()
 				case 'x':
 					$environment['SKIP_SLOW_TESTS'] = 1;
 					break;
+				case '--offline':
+					$environment['SKIP_ONLINE_TESTS'] = 1;
+					break;
 				//case 'w'
 				case '-':
 					// repeat check with full switch
@@ -689,6 +692,8 @@ function save_or_mail_results()
 
     -x          Sets 'SKIP_SLOW_TESTS' environmental variable.
 
+    --offline   Sets 'SKIP_ONLINE_TESTS' environmental variable.
+
     --verbose
     -v          Verbose mode.