[api] Adding support for Vm Sofware subcollection

- Query via /api/vms/#/software
- Optionally query via /api/vms/# --expand=software
- Updated spec requests/api/vms_spec.rb to test software subcollection
- Added FactoryGirl guest_application factory
PR Review changes

- spacing out blocks in specs
- going to semver versioning, so v1.0.0-pre

https://trello.com/c/PkUsXZx1
Merge pull request #1135 from abellotti/rest_api_vm_software

[api] Adding support for Vm Software subcollection