Add uuid for test server

Prevents it generation during tests running and failure for
make distcheck when config file is read only.
Fix tests temp directory path
Fix relative include path for couch_eunit.hrl
Move couch_eunit.hrl.in to include directory

Because include path "." has higher priority than any other custom
paths, generated during `configure` phase couch_eunit.hrl contains
build and source paths which aren't used for `make distcheck` causing
various failures.
Ensures that .test_design directory becomes created
Handle test_cfg_register daemon path in special way

During make distcheck test_cfg_register binary become separated from
others fixtures and becomes available by ?BUILDDIR path, not ?SOURCEDIR
as others are.
Simplify os_daemon_configer.escript

There is no need to start couch_config, init code paths and include
anything, just need to make ejson beams available.
More etap cleanup
Fix Makefile rules for `make distcheck`