Metro: Update attachment handling to include MatterAttachmentShowOnInternetPage and MatterAttachmentPrintWithReports

[hancush]

I submitted in a patch in #332 to skip attachments if MatterAttachmentShowOnInternetPage is False. This solved an immediate need to suppress an attachment, but it would be better to handle this case similarly to the way we handle private bills: Scrape a record of the attachment, but don't expose it downstream in Councilmatic. This is complicated a bit because there is a second flag, MatterAttachmentPrintWithReports, that indicates whether an attachment should be included in board report packets. Clarifying with Metro whether these attributes are always in sync, or if there may be a case where they don't want to show an attachment on the site but do want to include it in packets.

Update: Per Metro, these attributes should stay in sync, so it may be feasible to use one (show on internet page) to determine whether to suppress an attachment.