remoteui: copy http_proxy settings
http_proxy settings of current repo's .hg/hgrc should be available
on remoteui, so that the httprepo can use them when pulling via http.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.