refactor-864370: Fix Settings.getSetting bug
refactor-864370: Fix Settings.getSetting bug

In GCLI settings names are short simple things, bug prefs in Firefox are
generally longer, so there is a prefix that we use when a GCLI setting
is stored in a Firefox pref. getSetting was failing to use this prefix.

Signed-off-by: Joe Walker <7a17872fbb32c7d760c9a16ee3076daead11efcf@mozilla.com>

joewalker/gcli,mozilla/gcli,mozilla/gcli,joewalker/gcli,mozilla/gcli