Install ia32-libs package very early on 64-bit OS

Support of **ELF 32-bit binaries** is still needed nowadays on a 64-bit multi-purpose server, such as bluebox.

Any travis job that currently fails with error like following is probably depending on a 32-bit binary:

```
Cannot run program "/home/travis/.../.../some-binary-file": error=2, No such file or directory.
```
Example: https://github.com/travis-ci/travis-worker/issues/56

Please: 
 * validate that provisioning runs fine with bluebox true base image and chef runlist.
 * tell me if it needs more comments/documentation
 * you also can try to shift a bit later the installation of this package, if there is any reason to do it (which one?)