This is a followup patch for D9697 which applies the changes to the addon reporistory.
Almost all of the changes are in rigify, but there is one small change in "curve_tools"
and two trivial changes in IO addons.
I don't have much experience with Rigify, so I haven't been able to do the most thorough
testing, but I have tested by creating rigs and inspecting their custom properties.
The changes are relatively simple anyway, it's just slightly changing the functions used
to create and copy custom property UI data.