Laravel 5.6 updates

Travis config update

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

vendor/symfony/var-dumper/CHANGELOG.md

@@ -1,6 +1,25 @@
 CHANGELOG
 =========
 
+4.1.0
+-----
+
+ * added a `ServerDumper` to send serialized Data clones to a server
+ * added a `ServerDumpCommand` and `DumpServer` to run a server collecting
+   and displaying dumps on a single place with multiple formats support
+ * added `CliDescriptor` and `HtmlDescriptor` descriptors for `server:dump` CLI and HTML formats support
+
+4.0.0
+-----
+
+ * support for passing `\ReflectionClass` instances to the `Caster::castObject()`
+   method has been dropped, pass class names as strings instead
+ * the `Data::getRawData()` method has been removed
+ * the `VarDumperTestTrait::assertDumpEquals()` method expects a 3rd `$context = null`
+   argument and moves `$message = ''` argument at 4th position.
+ * the `VarDumperTestTrait::assertDumpMatchesFormat()` method expects a 3rd `$context = null`
+   argument and moves `$message = ''` argument at 4th position.
+
 3.4.0
 -----