Actually bump version to 0.2.0

In a7d371d49211be4c8e45c373f172bafa9e93e538 I omitted to bump the
version to 0.2.0 in `lib/vcloud/core/version.rb`.
Merge pull request #36 from alphagov/69995588-namespace_under_core

[#69995588] Actually bump version to 0.2.0