Refactor how configs are loaded and passed to daemons.
Add conf.d support. So you can have an /etc/swift/object-server.conf.d
or /etc/swift/object-server/1.conf.d, and any .conf files under it
will be loaded as one config.
conf.d files are combined in filename lexigraphical order, with any
sections in later files replace existing section entries.
Change-Id: I78d7e5449cd0b62df9dfdb25616a2d4c91159f8c