Dynamic properties & reusable command line implementation

Functional implementation of a stripped down onetemplate provider with dynamic property lookup and a restructured way to call opennebula commands. All `.erb` templates are moved to the respective module & this changes adds 3 (stubbed) responses from a »real world« opennebula instance to run integration tests.

Testsuite is passing & adding + removing templates inside of a test vm works fine.

Nevertheless I'd like to have your feedback on this one – If it's fine with you, give a quick :+1: and I'll start porting the other providers to support the new `Puppet::Util::Opennebula::CLI`.