add config support for url and project folder to watch

    #to-do
    - set mismatch tolerance to 0
    - fix diff image rendering
    - incorrect filenames to be fixed
    - add config support for url and project folder to watch (done)
    --- add symbolic link to the project folder linking to the repo
    --- add livereload to the link (may not be feasible)
    - segregate screefly into its own repo