Handle namespaced projects in SSE server
    
    The SSE server's code for parsing the URL to get to the project
    does not handle namespacing. With this, it does. I tried to
    figure out the 'rules' for the path as best I could from other
    code in the project.
    
    Also refactor a bit to split out a path parsing function and
    separate object finding functions, and be more explicit about
    the specific object types we support.
    
    Also add a test suite for the streaming server, and update all
    docs, Ansible play, spec file etc. for the rename from
    'pagure-stream-server' to 'pagure_stream_server'.
    
    Fixes https://pagure.io/pagure/issue/1532
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>