use Lwt_log everywhere
Merge branch 'master' into lwt_log

Conflicts:
	src/lib/eliom_client.client.ml
Merge branch 'master' into lwt_log

Conflicts:
	src/lib/eliom_lib.client.ml
Remove useless code of debug
Misc: remove dead code
Misc: clean comment
Misc: improve log in Eliom_client
Eliom_lib: bring back deprecated function
Eliom_lib_base: bring back Lwt_ops
Merge pull request #117 from ocsigen/lwt_log

use Lwt_log everywhere