(AIX) Replace RPM SemVer comparisons with versioncmp

Prior to this commit, the RPM package provider was using SemVer
for determining if version numbers less than specific versions to
enable or disable specific flags. Unfortunately, SemVer requires
version numbers to have, at a minimum, x.y.z and several releases
of RPM only have x.y, causing SemVer to barf.  This commit retains
the logic (and adds tests), but uses the more lenient
`Puppet::Util::Package.versioncmp` instead.

Sprintly: fix ticket:252
Merge pull request #1428 from jeffweiss/ticket/aix/252_rpm_says_semantic_versioning_is_pedantic_versioning

(AIX) Replace RPM SemVer comparisons with versioncmp