Add common internet filetypes to Voila.file_whitelist configuration

[tdstein]

Add JavaScript (and possibly others) to the file whitelist option when launching voila applications.

--VoilaConfiguration.file_whitelist=<list-item-1>...
    List of regular expressions for controlling which static files are served.
    All files that are served should at least match 1 whitelist rule, and no
    blacklist rule Example:
    --VoilaConfiguration.file_whitelist="['.*\.(png|jpg|gif|svg)', 'public.*']"
    Default: ['.*\\.(png|jpg|gif|svg)']