mozilla packages: Fix and normalize SRC_URI

mozilla packages: Fix and normalize SRC_URI

As per gentoo bug 557040, upstream dropped their FTP archive.  This
commit cleans up all MOZ_*_URI specifications in mozilla ebuilds
to match one-another.  Ebuilds now use MOZ_HTTP_URI and
http://archive.mozilla.org/ ; adjusted ebuilds include:

www-client/firefox-38.1.1
www-client/firefox-39.0.3
www-client/firefox-bin-38.1.1
www-client/firefox-bin-39.0.3
mail-client/thunderbird-38.1.0
mail-client/thunderbird-bin-38.1.0
www-client/seamonkey-2.33.1-r1
www-client/seamonkey-bin-2.33.1
www-client/seamonkey-bin-2.33.1-r1

Package-Manager: portage-2.2.20