To itest our autolooper, we need to be able to trigger dispatch on
demand. This functionality is included in a separate rpc server behind
a dev flag. Since it is unlikely that we need to split loop into
multiple rpc servers, this commit simply adds an additional debug server
rather than opting for a full subserver setup.
Build executables are suffixed with 'debug' because we cannot
create a loopd executable in the root repo dir, since there is an
already existing loopd executable. Add build to travis.
