[Bug-gnuzilla] Free addons for IceCat list addition/change

[BM-2cWkkpvnbPh22whk4ZrXLCdLnN4syBd8vL]

The addon "Tab Kit" is not compatible with GNU IceCat 17 & 24 (The only
ones that I have tested it with) and the author has seemed to disapear as
well.
There is a TabKit 2nd Edition that is compatible with those versions and
it is licensed under the GPLv2.

Links to addon page: http://code.google.com/p/tabkit-2nd-edition/
                     
https://addons.mozilla.org/en-US/firefox/addon/tabkit-2nd-edition/


Also this addon which is not on the list has a custom license:
MPL 1.1/GPL 2.0/LGPL 2.1

Link to addon: https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/
Link to license:
https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/license/0.14.2014051101

I wonder if that addon is okay to add to the list? I'm not sure though.

Thank you for reading!