Poll all Jira issues and enable filtering by issuetype

Currently we restrict polling of Jira issues to only ones with the issuetype set to Bug. This ignores polling 'Story' issues, though these issues may be desirable to pull into CI Bug Log as well.

As it stands, this requires minimal effort in regards to the polling aspect. I just need to remove the query parameter that restricts getting only Bugs from Jira. I can use the custom_fields_map/custom_fields feature to pull in the issuetype for Jira bugs, and that will set it in the custom_field for the Bug model instance.

In regards to filtering, filtering on custom fields is already added, so the filter 'custom_fields.issuetype = "Bug"' could already be used to filter.

So I already have a patch that just removes the 'issuetype = "Bug"' JQL query, and then I'd add 'issuetype' to the Jira custom_fields map and everything will be ready to go.

Any additional features or implementation details I'm missing here, @mupuf?