Laravel 5.6 updates

Travis config update

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

vendor/dragonmantank/cron-expression/.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.yml]
+indent_style = space
+indent_size = 2