fix(compatibility): Conflict with other modules

[minorOffense]

Other modules declaring packages conflict with this module. Instead, switch to ensure_packages()from puppetlabs-stdlib.

You'll need to add the dependency to puppetlabs-stdlib in the module info.

[igoraj]

Sorry for late response. You mean when other modules don't use ensure_packages or if defined() syntax they are conflicting with this one?
Well, I can certainly see how this can be an issue, but I'm a bit worried because ensure_packages appeared only in stdlib 4.x which drops support for Puppet 2.7 (which is default in Ubuntu 12.04LTS, still widely used).

[minorOffense]

Exactly. The declarations from other puppet modules using defined() create catalog errors.

What about a conditional block that checks the version of stdlib installed? If ensure_packages is there use it, fallback otherwise.

[igoraj]

Actually what I said yesterday is not true. It seems they had the same problem, and decided in the end not to break backwards compatibility in 4.x. (read more here). When stdlib 5.x comes out it will drop support for older versions of puppet. So I can merge your PR and add dependency on stdlib 4.x with no issues (at least I hope there will not be any :))