Disable "will not be installed because it does not provide secure updates" in firefox

OK so I was trying to install some addons into firefox and kept getting "will not be installed because it does not provide secure updates" and no matter what i tried it wouldnt damn well let me.

So how did I get around it? simple.

goto about:config in your urlbar
this takes you to the firefox configuration file

now
right click in the list of keys and select "new > boolean"
put in the name as "extensions.checkUpdateSecurity" without the "s

set the value to "false" and your set!
don't even need to restart firefox (but do it if you can just in case!)

Now, because I was being dozy I screwed up and did "new > string" and you cant change the type and you cant delete the damn thing. So here is a simple explanation of how to delete a key from the about:config ***WARNING*** DON'T DO THIS FOR KEYS YOU KNOW NOTHING ABOUT!! **/WARNING**

go and find your pref.js file for me under Linux it was in
/home/freakyclown.mozilla/firefox/i13d0s50.default/prefs.js

find the key you want to delete and just remove it!
restart firefox and your done (as long as you didn't remove something you shouldnt have)