Add specs for IC Serialization and Deserialization

[agrare]

Improve test coverage for IC#to_hash and IC#from_hash.

TODO:

• [x] Test lazy references to other collections
• [x] Test arrays of lazy references
• [ ] Test partial data

[agrare]

This gets the test coverage of InventoryCollection::Serialization up to 95% from 34% and found some bugs in the process

[miq-bot]

Checked commits https://github.com/agrare/inventory_refresh/compare/537149f238b4c5a0d487311936bca8b7ba0b9d82~...267d06bc9c7b925c009f097f548703344c42e16b with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0 4 files checked, 0 offenses detected Everything looks fine. :star:

[Ladas]

@agrare I am moving the core serialization specs here in https://github.com/ManageIQ/inventory_refresh/pull/19, so it shouldn't be 30%?

[agrare]

This is covered by some specs that have been added