chore(cleanup) some non-functional maintenance

- add 'docs' to rockspec for `luarocks doc date` to work
- config trim trailing whitespace
- trim trailing whitespace
- remove test file since it was moved to spec/

date-2.1.2-3.rockspec

@@ -25,6 +25,7 @@ build = {
    type = "builtin",
    modules = {
       date = "src/date.lua"
-   }
+   },
+   copy_directories = { "docs" },
 }