pagure_bot: don't double-parse commands
    
    Before, we filtered commands from a comment text, but still kept them in a text
    form, and so when we wanted to process them in a later stage, we needed to parse
    them again (or rely on unsafe modifications). This patch avoids that by using
    data containers for parsed commands, and so the later stages can directly access
    structured data instead of parsing the text again.
    
    Merges: https://pagure.io/fedora-qa/blockerbugs/pull-request/164
    Related: https://pagure.io/fedora-qa/blockerbugs/pull-request/163