Promote array arguments to arrays at the time they are retrieved

Waiting until they have been mixed into the config is too late
when an argument can be an object.

Fixes #491.

(cherry picked from commit afd2570)

Author: csnover

lib/executors/PreExecutor.js

@@ -105,6 +105,13 @@ define([
 				kwArgs = parseArgs.fromCommandLine(process.argv.slice(2));
 			}
 
+			[ 'environments', 'functionalSuites', 'reporters', 'suites' ].forEach(function (name) {
+				var value = kwArgs[name];
+				if (value != null && !Array.isArray(value)) {
+					kwArgs[name] = value === '' ? [] : [ value ];
+				}
+			});
+
 			this.getArguments = function () {
 				return kwArgs;
 			};
@@ -225,13 +232,6 @@ define([
 					}
 				}
 
-				[ 'environments', 'functionalSuites', 'reporters', 'suites' ].forEach(function (name) {
-					var value = config[name];
-					if (value != null && !Array.isArray(value)) {
-						config[name] = value === '' ? [] : [ value ];
-					}
-				});
-
 				if (has('host-browser') && args.loaders && args.loaders['host-browser']) {
 					util.assertSafeModuleId(args.loaders['host-browser']);
 				}