Relax vCloud Tools Tester dependency

Allow vCloud Launcher to depend on any vCloud Tools Tester between 0.1 and (up to but not including) 0.2.
Merge pull request #54 from gds-operations/bump-tools-version

Relax vCloud Tools Tester dependency
Update CHANGLOG to reflect recent changes

Ready for version 0.2.0.
Depend on vCloud Core version 0.6.0

Necessary because of the changes to
`Vcloud::Core::Vm::configure_guest_customization_section`.
Version 0.2.0

Minor version bump because these changes break backwards compatibility
but we're not yet at version 1.0 so our API should be considered
unstable.