Issue #326 - supporting upgrade files and version

[emilianodellacasa]

Solving issue #326 allowing Zold to upgrade itself using rb scripts.

I used the tests that had already been written but skipped at the moment.

Please note that I had to disable Eval check in Rubocop to avoid the code smell: in fact, using the "eval" function is a potential security breach, but it should be ok as we are executing only scripts that are in a specific directory of the repository.

[0crat]

Job #496 is now in scope, role is REV

[0crat]

@yegor256/z everybody who has role REV is banned at #496; I won't be able to assign anyone automatically; consider assigning someone manually (as in §19), or invite more people (as in §51), or remove the job from the scope (as in §14)

[0crat]

@yegor256/z everybody who has role REV is banned at #496; I won't be able to assign anyone automatically; consider assigning someone manually (as in §19), or invite more people (as in §51), or remove the job from the scope (as in §14)

[0crat]

@yegor256/z everybody who has role REV is banned at #496; I won't be able to assign anyone automatically; consider assigning someone manually (as in §19), or invite more people (as in §51), or remove the job from the scope (as in §14)

[0crat]

This pull request #496 is assigned to @tsuhachev/z, here is why; the budget is 15 minutes, see §4; please, read §27 and when you decide to accept the changes, inform @yegor256/z (the architect) right in this ticket; if you decide that this PR should not be accepted ever, also inform the architect; this blog post will help you understand what is expected from a code reviewer; there will be no monetary reward for this job

[0crat]

@tsuhachev/z this job was assigned to you 5days ago. It will be taken away from you soon, unless you close it, see §8. Read this and this, please.