Firefox automatic configuration.

ipa.cfg needs to be installed in the Firefox root directory
(/usr/lib/firefox-version). It can be a symlink somewhere else. We install
the actual file into /usr/share/ipa.

ipa.js contains the javascript that sets the desired configuration.

The Firefox all.js needs to be modified to set:

pref('general.config.obscure_value', 0);
pref('general.config.filename', 'ipa.cfg');

First need to remove any existing values for these.

For more information on autoconfiguration, see:
http://mit.edu/~firefox/www/maintainers/autoconfig.html