MDL-49456 behat: Fixed following issues in parallel run

1. Parallel run without feature should exit with success
2. Updated exit codes to be more clear for each process
3. Fixed wwwroot and dataroot while executing with tags
4. Added support for running scenario/feature
5. Added support for or'ing tags
6. Added support for running single behat site
7. Fixed wrong example in help
8. Use parallel run only when parallel > 1
9. Exit showing behat site is not installed
10. Exit with error, if not a valid option
11. Added usage in help to explain how to use command
12. run.php should be able to run from any path
13. Pass all arguments to single run

admin/tool/behat/cli/util.php

@@ -68,15 +68,18 @@ list($options, $unrecognized) = cli_get_params(
 $help = "
 Behat utilities to manage the test environment
 
+Usage:
+  php util.php [--install|--drop|--enable|--disable|--diag|--updatesteps|--help] [--parallel=value [--maxruns=value]]
+
 Options:
 --install      Installs the test environment for acceptance tests
 --drop         Drops the database tables and the dataroot contents
 --enable       Enables test environment and updates tests list
 --disable      Disables test environment
 --diag         Get behat test environment status code
+--updatesteps  Update feature step file.
 -j, --parallel Number of parallel behat run operation
 -m, --maxruns  Max parallel processes to be executed at one time.
---updatesteps  Update feature step file.
 
 -h, --help     Print out this help
 
@@ -205,8 +208,12 @@ if ($options['install']) {
 } else if ($options['disable']) {
     echo "Acceptance tests environment disabled for " . $options['parallel'] . " parallel sites" . PHP_EOL;
 
+} else if ($options['diag']) {
+    // Valid option, so nothing to do.
 } else {
     echo $help;
+    chdir($cwd);
+    exit(1);
 }
 
 chdir($cwd);