refactor Fuel plugin builder validator

[Ilya Kutukov]

In Fuel plugin builder validator due partial inheritance of different validators versions is very hard to understand what checks is applied to what files.
Also it's possible to output only one error and merely possible to output warnings and informational messages during plugin validation.
Current validator structure is hard to extend with plugins multi-release support and notifications related to plugin packages v5.0.0.
So validator refactoring is required.

[Ilya Kutukov (ikutukov)]

WIP patch
https://review.openstack.org/#/c/281291/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/290564

[OpenStack Infra (hudson-openstack)]

Change abandoned by Fuel DevOps Robot (<email address hidden>) on branch: master
Review: https://review.openstack.org/290564
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Fuel DevOps Robot (<email address hidden>) on branch: master
Review: https://review.openstack.org/281291
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Dmitry Pyzhov (dpyzhov)]

Technical debt, doesn't affect real users. Removing from Mitaka release.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Fuel DevOps Robot (<email address hidden>) on branch: master
Review: https://review.openstack.org/290564
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Fuel DevOps Robot (<email address hidden>) on branch: master
Review: https://review.openstack.org/281291
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ilya Kutukov (<email address hidden>) on branch: master
Review: https://review.openstack.org/355572
Reason: History should be purged

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/365418

[OpenStack Infra (hudson-openstack)]

Change abandoned by Fuel DevOps Robot (<email address hidden>) on branch: master
Review: https://review.openstack.org/365418
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.