lua: add 5.3.x serie
luajit: add 2.1 branch
luarocks: bump to version 2.2.0beta1

Config.in: new default repository for rock
luarocks: move the option --deps-mode

from `luarocks make` command to the LuaRocks config file.

This change and the merge of PR https://github.com/keplerproject/luarocks/pull/236
in LuaRocks 2.2.0 avoid the confusing message "Missing dependency"
lua-messagepack: bump to version 0.3.1
lua-posix: bump to version 32

the patch was merged upstream,
see https://github.com/luaposix/luaposix/pull/117