* Re-enable railroader static analyzer

This re-enables the use of the "railroader" static analyzer.
Unfortunately "gem install" doesn't honor Gemfile.lock, only Gemfile.
Implement some workarounds so we can get this working again.
(The intent is to have a cleaner approach longer-term, but we
want to get this working *now*).

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

* Rerun checks

This change is irrelevant, but it forces re-execution of tests.

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

* script/report_code_statistics: Fix warning

"bundle show" is deprecated, use "bundle list" instead.

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

* .robocop.yml: Don't check railroader/ if present

Railroader has its own requirements, don't check it as
part of CII Best Practices.

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

* Modify rake script to work properly

Ignore the "railroader/" directory (if present)
in various static checks.

Modify yaml_syntax_check to ignore railroader *and*
have it fail on failure (the later greps hid failures).

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>