Fix .travis.yml

Switched to a more bare-bones language environment.
(Lua is not supported so it defaults to Ruby)

Update aptitude repositories before installing dependencies.

.travis.yml

@@ -1,4 +1,4 @@
-language: lua
+language: d
 
 notifications:
   email: false
@@ -8,6 +8,7 @@ env:
     - secure: "kFhU+DZjhq/KbDt0DIDWnlskXMa12miNelmhhy30fQGgVIdiibDGKMNGyLahWp8CnPu1DARb5AZWK2TDfARdnURT2pgcsG83M7bYIY6cR647BWjL7oAhJ6CYEzTWJTBjeUjpN/o4vIgfXSDR0c7vboDi7Xz8ilfrBujPL2Oi/og="
 
 install:
+  - sudo apt-get -y update
   - sudo apt-get -y install lua5.1 lua-doc
 
 script: