Jun Wu <quark@fb.com> [Fri, 17 Mar 2017 09:19:56 -0700] rev 31481
ui: move configlist parser to config.py
The list parser is complex and reusable without ui. Let's move it to
config.py.
This allows us to parse a list from a "pure" config object without going
through ui. Like, we can make "_trustusers" calculated from raw configs,
instead of making sure it's synchronized by calling "fixconfig"s.