test 5.1, 5.2 and luajit

.travis.yml

@@ -5,10 +5,14 @@ addons:
   apt:
     packages:
     - lua5.1
+    - lua5.2
+    - luajit
 
 branches:
   only:
     - master
 
 script:
-  - lua tests/runner.lua
+  - lua5.1 tests/runner.lua
+  - lua5.2 tests/runner.lua
+  - luajit-2.0.0-beta9 tests/runner.lua