Install Firefox Nightly binaries from Mozilla

Installation process is similar to the one for Thunderbird Daily (see this blog post).

differences:

• binary download link:
  # wget "https://download.mozilla.org/?product=firefox-nightly-latest-ssl&os=linux64&lang=en-US" -O firefox-nightly.tar.bz2
• icon link:
  # wget http://www.iconspedia.com/dload.php?up_id=146406 -O ~/.icons/Mozilla-Firefox-Nightly-256.png
• [code languag="bash" title="desktop entry" fold="true"]
  # cat ~/.local/share/applications/firefox-nightly.desktop
  [Desktop Entry]
  Version=1.0
  Name=Firefox Nightly
  GenericName=Web Browser
  Comment=Browse the Web
  Exec=firefox-nightly %u
  Icon=Mozilla-Firefox-Nightly-256.png
  Terminal=false
  Type=Application
  MimeType=text/html;text/xml;application/xhtml+xml;application/vnd.mozilla.xul+xml;text/mml;x-scheme-handler/http;x-scheme-handler/https;
  StartupNotify=true
  Categories=Network;WebBrowser;
  Keywords=web;browser;internet;
  Actions=new-window;new-private-window;

  [Desktop Action new-window]
  Name=New Window
  Exec=firefox-nightly --new-window %u

  [Desktop Action new-private-window]
  Name=New Private Window
  Exec=firefox-nightly --private-window %u
  [/code]