integrated home page javascripts and updated links

fix issue where output dir cannot be deleted
added image assets
made all img links relative
revamp component system

distinction between require/include:
    require'd components will always set their field value in the
        template.
    include'd components will only set the field value if it doesn't
        exist. This allows {posts} to default for a list of recent
        posts, as well as a placeholder for rendering a single post
refactor metadata system to make things simpler
solidified tag handling with active_tag component

cleaned up ambiguity around the slug field
    it is used as the output filename. if slug is not provided,
    a slugified version of the original filename is used.
fixed some debugging output
cleaning up content folder