Move Vcloud::QueryRunner under Vcloud::Core

Move Vcloud::QueryRunner under Vcloud::Core to comply with breaking
changes introduced in vcloud-core version 0.2.0.

Also bumps the dependency on vcloud-core in the Gemspec so that we use
version 0.2.0, and bumps vcloud-net_launcher to version 0.1.0.

Prefer a minor version bump for vcloud-net_launcher (as opposed to a
patch version bump) to make it clearer that the changes in vcloud-core
broke backwards compatibility and that it's preferable to upgrade.
Fix indenting in CHANGELOG for consistency

Fix indenting in `CHANGELOG.md` for consistency with other tools[1][2].

[1]:
https://raw.githubusercontent.com/alphagov/vcloud-edge_gateway/master/CHANGELOG.md
[2]:
https://raw.githubusercontent.com/alphagov/vcloud-launcher/master/CHANGELOG.md
Merge pull request #15 from alphagov/69995588-namespace_under_core

[#69995588] Namespace Vcloud::QueryRunner under Vcloud::Core