Parliament

This release adds the ability to have custom auditors. This is documented in the README, showing an example of how to create an auditor to generate findings for any policy that grants access to a sensitive S3 bucket: https://github.com/duo-labs/parliament#custom-auditors

This also changed how the filtering works for ignoring findings, which gives some greater control over that, by changing what had been a search for a substring into a full regex match. The regex match does mean that a search for a substring like `s3:*` now must be written as `.*s3:\\*.*` (note that `.*` are added to the ends so this function as a substring lookup, and the original `*` needs to be double-escaped as `\\*`).

Updates privileges. AWS changed their doc format, so a new method was needed to scrape these, which was borrowed from work done by kmcquade on policy_sentry

Other changes:
danielpops Fixed a typo

Exit status now only uses a 1 to indicate findings (0 if there are no findings). The last release set the exit status to the number of findings, but that might not work in shell environments if there are over 255 findings. This was pointed out by Ben Bridts‏: https://twitter.com/benbridts/status/1205465492984647680

Parliament now supports a custom config file so you can change the text or severity of issues, or filter them out entirely. For usage examples see the docs at https://github.com/duo-labs/parliament#custom-config-file

Bug fixes
- Allow aws:MultiFactorAuthAge tested against a number
- Allow Null condition to be used without findings about the items that are being checked
- Allow policies to have unquoted Bool values (true and false can be used without quotes)

Fixes an exception for unknown prefixes and actions introduced in 0.3.2