Improved idempotency for firmware bundle uploads

[fgbulsoni]

Description

Adds a validation using the name of the file being uploaded against the resourceId of all firmwares present in the appliance, in order to detect if a file has been uploaded already or not.

Issues Resolved

153

Check List

• [X] New functionality includes testing.
  • [X] All tests pass ($ rake test).
• [X] New functionality has been documented in the README if applicable.
  • [X] New functionality has been thoroughly documented in the examples (please include helpful comments).
• [X] Changes are documented in the CHANGELOG.

[fgbulsoni]

@frippe75 This should fix #153. Please let us know if you run into further issues. Cheers :octocat: ✨