Fix and document the verifier

[microstudi]

Fixes the verifier for ballots or election logs (a tar file).

• Verifying a single ballot requires python and the library electionguard to be installed.
• Verifying a tar election file requires java and to compile a JAR file.

I've added instructions in the README file to documentat all of this, is not ideal but it can save you a lot of time.

fixes #231 supersedes #192 requires #310 to be merged to fix the rubocop issues

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (be58cb5) 69.57% compared to head (fb1b4f4) 69.57%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #311 +/- ## ======================================== Coverage 69.57% 69.57% ======================================== Files 96 96 Lines 1630 1630 ======================================== Hits 1134 1134 Misses 496 496 ```

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