Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/symfony/console/Input/ArgvInput.php

@@ -146,11 +146,6 @@ class ArgvInput extends Input
 
         if (false !== $pos = strpos($name, '=')) {
             if (0 === \strlen($value = substr($name, $pos + 1))) {
-                // if no value after "=" then substr() returns "" since php7 only, false before
-                // see http://php.net/manual/fr/migration70.incompatible.php#119151
-                if (\PHP_VERSION_ID < 70000 && false === $value) {
-                    $value = '';
-                }
                 array_unshift($this->parsed, $value);
             }
             $this->addLongOption(substr($name, 0, $pos), $value);