CLI: Analyzers with DiagnosticSeverity.Info

[Kasperki]

IAnalyzerExporter have hardcoded DiagnosticInfo.DiagnosticInfoSeverity MinimalSeverity.
Make that configurable.

[Kasperki]

I have made this update to my dev branch, but I do not want to make Pull request, until @vad710 can merge current pull requests, so I can rebase and this change easier to merge.

Cleaned diagnostics descriptions: Kasperki@885dd8b
Added command line parser: Kasperki@4b8f846
And finally Minimali Severity can be given as CLI argument: Kasperki@0327796

[vad710]

I will try to get all the PRs wrapped up this week

[vad710]

Should be good to submit the new commits